Nullability refinements on private and static methods

Based on IntelliJ IDEA 2017.3 introspection results.

Issue: SPR-15756

spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/AbstractAutoProxyCreator.java

@@ -48,6 +48,7 @@ import org.springframework.beans.factory.config.ConfigurableBeanFactory;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.beans.factory.config.SmartInstantiationAwareBeanPostProcessor;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
 /**
@@ -543,6 +544,7 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	 * @see #setInterceptorNames
 	 */
 	private Advisor[] resolveInterceptorNames() {
+		Assert.state(this.beanFactory != null, "BeanFactory required for resolving interceptor names");
 		ConfigurableBeanFactory cbf = (this.beanFactory instanceof ConfigurableBeanFactory ?
 				(ConfigurableBeanFactory) this.beanFactory : null);
 		List<Advisor> advisors = new ArrayList<>();

spring-beans/src/main/java/org/springframework/beans/BeanWrapperImpl.java

@@ -205,7 +205,7 @@ public class BeanWrapperImpl extends AbstractNestablePropertyAccessor implements
 	 * @throws TypeMismatchException if type conversion failed
 	 */
 	@Nullable
-	public Object convertForProperty(Object value, String propertyName) throws TypeMismatchException {
+	public Object convertForProperty(@Nullable Object value, String propertyName) throws TypeMismatchException {
 		CachedIntrospectionResults cachedIntrospectionResults = getCachedIntrospectionResults();
 		PropertyDescriptor pd = cachedIntrospectionResults.getPropertyDescriptor(propertyName);
 		if (pd == null) {

spring-beans/src/main/java/org/springframework/beans/PropertyEditorRegistrySupport.java

@@ -541,6 +541,7 @@ public class PropertyEditorRegistrySupport implements PropertyEditorRegistry {
 			return this.registeredType;
 		}
 
+		@Nullable
 		private PropertyEditor getPropertyEditor(@Nullable Class<?> requiredType) {
 			// Special case: If no required type specified, which usually only happens for
 			// Collection elements, or required type is not assignable to registered type,

spring-beans/src/main/java/org/springframework/beans/PropertyValue.java

@@ -97,7 +97,7 @@ public class PropertyValue extends BeanMetadataAttributeAccessor implements Seri
 	 * @param original the PropertyValue to link to (never {@code null})
 	 * @param newValue the new value to apply
 	 */
-	public PropertyValue(PropertyValue original, Object newValue) {
+	public PropertyValue(PropertyValue original, @Nullable Object newValue) {
 		Assert.notNull(original, "Original must not be null");
 		this.name = original.getName();
 		this.value = newValue;
@@ -172,7 +172,7 @@ public class PropertyValue extends BeanMetadataAttributeAccessor implements Seri
 	 * Set the converted value of the constructor argument,
 	 * after processed type conversion.
 	 */
-	public synchronized void setConvertedValue(Object value) {
+	public synchronized void setConvertedValue(@Nullable Object value) {
 		this.converted = true;
 		this.convertedValue = value;
 	}

spring-beans/src/main/java/org/springframework/beans/factory/groovy/GroovyBeanDefinitionReader.java

@@ -459,21 +459,18 @@ public class GroovyBeanDefinitionReader extends AbstractBeanDefinitionReader imp
 		boolean hasClosureArgument = (args[args.length - 1] instanceof Closure);
 		if (args[0] instanceof Class) {
 			Class<?> beanClass = (Class<?>) args[0];
-			if (args.length >= 1) {
-				if (hasClosureArgument) {
-					if (args.length - 1 != 1) {
-						this.currentBeanDefinition = new GroovyBeanDefinitionWrapper(
-								beanName, beanClass, resolveConstructorArguments(args, 1, args.length - 1));
-					}
-					else {
-						this.currentBeanDefinition = new GroovyBeanDefinitionWrapper(beanName, beanClass);
-					}
-				}
-				else  {
+			if (hasClosureArgument) {
+				if (args.length - 1 != 1) {
 					this.currentBeanDefinition = new GroovyBeanDefinitionWrapper(
-							beanName, beanClass, resolveConstructorArguments(args, 1, args.length));
+							beanName, beanClass, resolveConstructorArguments(args, 1, args.length - 1));
 				}
-
+				else {
+					this.currentBeanDefinition = new GroovyBeanDefinitionWrapper(beanName, beanClass);
+				}
+			}
+			else  {
+				this.currentBeanDefinition = new GroovyBeanDefinitionWrapper(
+						beanName, beanClass, resolveConstructorArguments(args, 1, args.length));
 			}
 		}
 		else if (args[0] instanceof RuntimeBeanReference) {

spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractAutowireCapableBeanFactory.java

@@ -1556,7 +1556,7 @@ public abstract class AbstractAutowireCapableBeanFactory extends AbstractBeanFac
 	 * @param pvs the new property values
 	 */
 	protected void applyPropertyValues(String beanName, BeanDefinition mbd, BeanWrapper bw, PropertyValues pvs) {
-		if (pvs == null || pvs.isEmpty()) {
+		if (pvs.isEmpty()) {
 			return;
 		}
 
@@ -1649,7 +1649,9 @@ public abstract class AbstractAutowireCapableBeanFactory extends AbstractBeanFac
 	 * Convert the given value for the specified target property.
 	 */
 	@Nullable
-	private Object convertForProperty(Object value, String propertyName, BeanWrapper bw, TypeConverter converter) {
+	private Object convertForProperty(
+			@Nullable Object value, String propertyName, BeanWrapper bw, TypeConverter converter) {
+
 		if (converter instanceof BeanWrapperImpl) {
 			return ((BeanWrapperImpl) converter).convertForProperty(value, propertyName);
 		}

spring-beans/src/main/java/org/springframework/beans/factory/support/AutowireUtils.java

@@ -145,7 +145,6 @@ abstract class AutowireUtils {
 	 * @param requiredType the type to assign the result to
 	 * @return the resolved value
 	 */
-	@Nullable
 	public static Object resolveAutowiringValue(Object autowiringValue, Class<?> requiredType) {
 		if (autowiringValue instanceof ObjectFactory && !requiredType.isInstance(autowiringValue)) {
 			ObjectFactory<?> factory = (ObjectFactory<?>) autowiringValue;

spring-beans/src/main/java/org/springframework/beans/factory/xml/ParserContext.java

@@ -93,6 +93,7 @@ public final class ParserContext {
 		return this.readerContext.extractSource(sourceCandidate);
 	}
 
+	@Nullable
 	public CompositeComponentDefinition getContainingComponent() {
 		return (!this.containingComponents.isEmpty() ?
 				(CompositeComponentDefinition) this.containingComponents.lastElement() : null);

spring-context-support/src/main/java/org/springframework/cache/ehcache/EhCacheFactoryBean.java

@@ -205,7 +205,9 @@ public class EhCacheFactoryBean extends CacheConfiguration implements FactoryBea
 		String cacheName = getName();
 		if (cacheName == null) {
 			cacheName = this.beanName;
-			setName(cacheName);
+			if (cacheName != null) {
+				setName(cacheName);
+			}
 		}
 
 		// If no CacheManager given, fetch the default.

spring-context/src/main/java/org/springframework/context/annotation/CommonAnnotationBeanPostProcessor.java

@@ -597,7 +597,7 @@ public class CommonAnnotationBeanPostProcessor extends InitDestroyAnnotationBean
 			else if (embeddedValueResolver != null) {
 				resourceName = embeddedValueResolver.resolveStringValue(resourceName);
 			}
-			if (resourceType != null && Object.class != resourceType) {
+			if (Object.class != resourceType) {
 				checkResourceType(resourceType);
 			}
 			else {
@@ -642,7 +642,7 @@ public class CommonAnnotationBeanPostProcessor extends InitDestroyAnnotationBean
 					resourceName = Introspector.decapitalize(resourceName.substring(3));
 				}
 			}
-			if (resourceType != null && Object.class != resourceType) {
+			if (Object.class != resourceType) {
 				checkResourceType(resourceType);
 			}
 			else {
@@ -726,7 +726,7 @@ public class CommonAnnotationBeanPostProcessor extends InitDestroyAnnotationBean
 				}
 			}
 			Class<?> resourceType = resource.beanInterface();
-			if (resourceType != null && Object.class != resourceType) {
+			if (Object.class != resourceType) {
 				checkResourceType(resourceType);
 			}
 			else {

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassEnhancer.java

@@ -364,7 +364,6 @@ class ConfigurationClassEnhancer {
 			return resolveBeanReference(beanMethod, beanMethodArgs, beanFactory, beanName);
 		}
 
-		@Nullable
 		private Object resolveBeanReference(Method beanMethod, Object[] beanMethodArgs,
 				ConfigurableBeanFactory beanFactory, String beanName) {
 

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassUtils.java

@@ -35,6 +35,7 @@ import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.core.type.StandardAnnotationMetadata;
 import org.springframework.core.type.classreading.MetadataReader;
 import org.springframework.core.type.classreading.MetadataReaderFactory;
+import org.springframework.lang.Nullable;
 import org.springframework.stereotype.Component;
 
 /**
@@ -205,6 +206,7 @@ abstract class ConfigurationClassUtils {
 	 * or {@link Ordered#LOWEST_PRECEDENCE} if none declared
 	 * @since 5.0
 	 */
+	@Nullable
 	public static Integer getOrder(AnnotationMetadata metadata) {
 		Map<String, Object> orderAttributes = metadata.getAnnotationAttributes(Order.class.getName());
 		return (orderAttributes != null ? ((Integer) orderAttributes.get(AnnotationUtils.VALUE)) : null);

spring-core/src/main/java/org/springframework/core/ResolvableType.java

@@ -766,6 +766,7 @@ public class ResolvableType implements Serializable {
 		return (this.resolved != null ? this.resolved : fallback);
 	}
 
+	@Nullable
 	private Class<?> resolveClass() {
 		if (this.type == EmptyType.INSTANCE) {
 			return null;
@@ -1474,6 +1475,7 @@ public class ResolvableType implements Serializable {
 		}
 
 		@Override
+		@Nullable
 		public Type getOwnerType() {
 			return null;
 		}

spring-core/src/main/java/org/springframework/core/annotation/AnnotatedElementUtils.java

@@ -153,7 +153,6 @@ public class AnnotatedElementUtils {
 	 * @see #getMetaAnnotationTypes(AnnotatedElement, String)
 	 * @see #hasMetaAnnotationTypes
 	 */
-	@Nullable
 	public static Set<String> getMetaAnnotationTypes(AnnotatedElement element, Class<? extends Annotation> annotationType) {
 		Assert.notNull(element, "AnnotatedElement must not be null");
 		Assert.notNull(annotationType, "'annotationType' must not be null");
@@ -1114,7 +1113,7 @@ public class AnnotatedElementUtils {
 								processor.alwaysProcesses()) {
 							T result = processor.process(element, annotation, metaDepth);
 							if (result != null) {
-								if (processor.aggregates() && metaDepth == 0) {
+								if (aggregatedResults != null && metaDepth == 0) {
 									aggregatedResults.add(result);
 								}
 								else {
@@ -1126,7 +1125,7 @@ public class AnnotatedElementUtils {
 						else if (currentAnnotationType == containerType) {
 							for (Annotation contained : getRawAnnotationsFromContainer(element, annotation)) {
 								T result = processor.process(element, contained, metaDepth);
-								if (result != null) {
+								if (aggregatedResults != null && result != null) {
 									// No need to post-process since repeatable annotations within a
 									// container cannot be composed annotations.
 									aggregatedResults.add(result);
@@ -1144,7 +1143,7 @@ public class AnnotatedElementUtils {
 								containerType, processor, visited, metaDepth + 1);
 						if (result != null) {
 							processor.postProcess(currentAnnotationType, annotation, result);
-							if (processor.aggregates() && metaDepth == 0) {
+							if (aggregatedResults != null && metaDepth == 0) {
 								aggregatedResults.add(result);
 							}
 							else {
@@ -1154,7 +1153,7 @@ public class AnnotatedElementUtils {
 					}
 				}
 
-				if (processor.aggregates()) {
+				if (aggregatedResults != null) {
 					// Prepend to support top-down ordering within class hierarchies
 					processor.getAggregatedResults().addAll(0, aggregatedResults);
 				}
@@ -1237,9 +1236,10 @@ public class AnnotatedElementUtils {
 		return null;
 	}
 
-	private static <T> T searchOnInterfaces(Method method, Class<? extends Annotation> annotationType,
-			String annotationName, Class<? extends Annotation> containerType, Processor<T> processor,
-			Set<AnnotatedElement> visited, int metaDepth, Class<?>[] ifcs) {
+	@Nullable
+	private static <T> T searchOnInterfaces(Method method, @Nullable Class<? extends Annotation> annotationType,
+			@Nullable String annotationName, @Nullable Class<? extends Annotation> containerType,
+			Processor<T> processor, Set<AnnotatedElement> visited, int metaDepth, Class<?>[] ifcs) {
 
 		for (Class<?> iface : ifcs) {
 			if (AnnotationUtils.isInterfaceWithAnnotatedMethods(iface)) {
@@ -1495,7 +1495,6 @@ public class AnnotatedElementUtils {
 	static class AlwaysTrueBooleanAnnotationProcessor extends SimpleAnnotationProcessor<Boolean> {
 
 		@Override
-		@Nullable
 		public final Boolean process(@Nullable AnnotatedElement annotatedElement, Annotation annotation, int metaDepth) {
 			return Boolean.TRUE;
 		}

spring-core/src/main/java/org/springframework/core/annotation/AnnotationUtils.java

@@ -292,7 +292,6 @@ public abstract class AnnotationUtils {
 	 * @see java.lang.annotation.Repeatable
 	 * @see java.lang.reflect.AnnotatedElement#getAnnotationsByType
 	 */
-	@Nullable
 	public static <A extends Annotation> Set<A> getRepeatableAnnotations(AnnotatedElement annotatedElement,
 			Class<A> annotationType) {
 
@@ -1524,7 +1523,6 @@ public abstract class AnnotationUtils {
 	 * @see #synthesizeAnnotation(Map, Class, AnnotatedElement)
 	 * @see #synthesizeAnnotation(Annotation, AnnotatedElement)
 	 */
-	@Nullable
 	public static <A extends Annotation> A synthesizeAnnotation(Class<A> annotationType) {
 		return synthesizeAnnotation(Collections.<String, Object> emptyMap(), annotationType, null);
 	}

spring-core/src/main/java/org/springframework/core/convert/support/ObjectToObjectConverter.java

@@ -129,6 +129,7 @@ final class ObjectToObjectConverter implements ConditionalGenericConverter {
 		return (getValidatedMember(targetClass, sourceClass) != null);
 	}
 
+	@Nullable
 	private static Member getValidatedMember(Class<?> targetClass, Class<?> sourceClass) {
 		Member member = conversionMemberCache.get(targetClass);
 		if (isApplicable(member, sourceClass)) {
@@ -166,6 +167,7 @@ final class ObjectToObjectConverter implements ConditionalGenericConverter {
 		}
 	}
 
+	@Nullable
 	private static Method determineToMethod(Class<?> targetClass, Class<?> sourceClass) {
 		if (String.class == targetClass || String.class == sourceClass) {
 			// Do not accept a toString() method or any to methods on String itself
@@ -177,6 +179,7 @@ final class ObjectToObjectConverter implements ConditionalGenericConverter {
 				ClassUtils.isAssignable(targetClass, method.getReturnType()) ? method : null);
 	}
 
+	@Nullable
 	private static Method determineFactoryMethod(Class<?> targetClass, Class<?> sourceClass) {
 		if (String.class == targetClass) {
 			// Do not accept the String.valueOf(Object) method

spring-core/src/main/java/org/springframework/lang/NonNull.java

@@ -30,9 +30,8 @@ import javax.annotation.meta.TypeQualifierNickname;
  * Leverages JSR 305 meta-annotations to indicate nullability in Java to common tools with
  * JSR 305 support and used by Kotlin to infer nullability of Spring API.
  *
- * <p>Should be used at parameter, return value, and field level.
- * Methods overrides should repeat parent {@code @NonNull} annotations unless they behave
- * differently.
+ * <p>Should be used at parameter, return value, and field level. Method overrides should
+ * repeat parent {@code @NonNull} annotations unless they behave differently.
  *
  * <p>Use {@code @NonNullApi} (scope = parameters + return values) and/or {@code @NonNullFields}
  * (scope = fields) to set the default behavior to non-nullable in order to avoid annotating

spring-core/src/main/java/org/springframework/lang/NonNullApi.java

@@ -27,8 +27,9 @@ import javax.annotation.meta.TypeQualifierDefault;
 /**
  * A common Spring annotation to declare that parameters and return values
  * are to be considered as non-nullable by default for a given package.
- * Leverages JSR 305 meta-annotations to indicate nullability in Java to common tools with
- * JSR 305 support and used by Kotlin to infer nullability of Spring API.
+ *
+ * <p>Leverages JSR-305 meta-annotations to indicate nullability in Java to common
+ * tools with JSR-305 support and used by Kotlin to infer nullability of Spring API.
  *
  * <p>Should be used at package level in association with {@link Nullable}
  * annotations at parameter and return value level.

spring-core/src/main/java/org/springframework/lang/NonNullFields.java

@@ -21,15 +21,15 @@ import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
-
 import javax.annotation.Nonnull;
 import javax.annotation.meta.TypeQualifierDefault;
 
 /**
  * A common Spring annotation to declare that fields are to be considered as
- * non-nullable by default for a given package. Leverages JSR 305 meta-annotations to
- * indicate nullability in Java to common tools with JSR 305 support and used by Kotlin
- * to infer nullability of Spring API.
+ * non-nullable by default for a given package.
+ *
+ * <p>Leverages JSR-305 meta-annotations to indicate nullability in Java to common
+ * tools with JSR-305 support and used by Kotlin to infer nullability of Spring API.
  *
  * <p>Should be used at package level in association with {@link Nullable}
  * annotations at field level.

spring-core/src/main/java/org/springframework/lang/Nullable.java

@@ -30,9 +30,8 @@ import javax.annotation.meta.When;
  * some circumstance. Leverages JSR 305 meta-annotations to indicate nullability in Java
  * to common tools with JSR 305 support and used by Kotlin to infer nullability of Spring API.
  *
- * <p>Should be used at parameter, return value, and field level.
- * Methods overrides should repeat parent {@code @Nullable} annotations unless they behave
- * differently.
+ * <p>Should be used at parameter, return value, and field level. Methods override should
+ * repeat parent {@code @Nullable} annotations unless they behave differently.
  *
  * <p>Can be used in association with {@code NonNullApi} or {@code @NonNullFields} to
  * override the default non-nullable semantic to nullable.

spring-core/src/main/java/org/springframework/util/Base64Utils.java

@@ -20,8 +20,6 @@ import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.util.Base64;
 
-import org.springframework.lang.Nullable;
-
 /**
  * A simple utility class for Base64 encoding and decoding.
  *
@@ -90,9 +88,8 @@ public abstract class Base64Utils {
 	 * supported, i.e. neither Java 8 nor Apache Commons Codec is present at runtime
 	 * @since 4.2.4
 	 */
-	@Nullable
-	public static byte[] decodeUrlSafe(@Nullable byte[] src) {
-		if (src == null || src.length == 0) {
+	public static byte[] decodeUrlSafe(byte[] src) {
+		if (src.length == 0) {
 			return src;
 		}
 		return Base64.getUrlDecoder().decode(src);
@@ -130,7 +127,6 @@ public abstract class Base64Utils {
 	 * @throws IllegalStateException if Base64 encoding between byte arrays is not
 	 * supported, i.e. neither Java 8 nor Apache Commons Codec is present at runtime
 	 */
-	@Nullable
 	public static String encodeToUrlSafeString(byte[] src) {
 		return new String(encodeUrlSafe(src), DEFAULT_CHARSET);
 	}
@@ -143,7 +139,6 @@ public abstract class Base64Utils {
 	 * @throws IllegalStateException if Base64 encoding between byte arrays is not
 	 * supported, i.e. neither Java 8 nor Apache Commons Codec is present at runtime
 	 */
-	@Nullable
 	public static byte[] decodeFromUrlSafeString(String src) {
 		return decodeUrlSafe(src.getBytes(DEFAULT_CHARSET));
 	}

spring-core/src/main/java/org/springframework/util/ConcurrentReferenceHashMap.java

@@ -306,7 +306,6 @@ public class ConcurrentReferenceHashMap<K, V> extends AbstractMap<K, V> implemen
 	public boolean remove(Object key, final Object value) {
 		Boolean result = doTask(key, new Task<Boolean>(TaskOption.RESTRUCTURE_AFTER, TaskOption.SKIP_IF_EMPTY) {
 			@Override
-			@Nullable
 			protected Boolean execute(@Nullable Reference<K, V> reference, @Nullable Entry<K, V> entry) {
 				if (entry != null && ObjectUtils.nullSafeEquals(entry.getValue(), value)) {
 					if (reference != null) {
@@ -324,7 +323,6 @@ public class ConcurrentReferenceHashMap<K, V> extends AbstractMap<K, V> implemen
 	public boolean replace(K key, final V oldValue, final V newValue) {
 		Boolean result = doTask(key, new Task<Boolean>(TaskOption.RESTRUCTURE_BEFORE, TaskOption.SKIP_IF_EMPTY) {
 			@Override
-			@Nullable
 			protected Boolean execute(@Nullable Reference<K, V> reference, @Nullable Entry<K, V> entry) {
 				if (entry != null && ObjectUtils.nullSafeEquals(entry.getValue(), oldValue)) {
 					entry.setValue(newValue);

spring-core/src/main/java/org/springframework/util/FastByteArrayOutputStream.java

@@ -396,12 +396,6 @@ public class FastByteArrayOutputStream extends OutputStream {
 			else if (len == 0) {
 				return 0;
 			}
-			else if (len < 0) {
-				throw new IllegalArgumentException("len must be 0 or greater: " + len);
-			}
-			else if (off < 0) {
-				throw new IllegalArgumentException("off must be 0 or greater: " + off);
-			}
 			else {
 				if (this.currentBuffer == null) {
 					// This stream doesn't have any data in it...

spring-core/src/main/java/org/springframework/util/concurrent/FutureAdapter.java

@@ -51,7 +51,7 @@ public abstract class FutureAdapter<T, S> implements Future<T> {
 	 * @param adaptee the future to delegate to
 	 */
 	protected FutureAdapter(Future<S> adaptee) {
-		Assert.notNull(adaptee, "'delegate' must not be null");
+		Assert.notNull(adaptee, "Delegate must not be null");
 		this.adaptee = adaptee;
 	}
 
@@ -98,6 +98,7 @@ public abstract class FutureAdapter<T, S> implements Future<T> {
 				case SUCCESS:
 					return (T) this.result;
 				case FAILURE:
+					Assert.state(this.result instanceof ExecutionException, "Failure without exception");
 					throw (ExecutionException) this.result;
 				case NEW:
 					try {

spring-core/src/main/java/org/springframework/util/xml/XmlValidationModeDetector.java

@@ -165,6 +165,7 @@ public class XmlValidationModeDetector {
 	 * Consume the next comment token, update the "inComment" flag
 	 * and return the remaining content.
 	 */
+	@Nullable
 	private String consume(String line) {
 		int index = (this.inComment ? endComment(line) : startComment(line));
 		return (index == -1 ? null : line.substring(index));

spring-expression/src/main/java/org/springframework/expression/spel/ast/CompoundExpression.java

@@ -32,7 +32,7 @@ import org.springframework.lang.Nullable;
  */
 public class CompoundExpression extends SpelNodeImpl {
 
-	public CompoundExpression(int pos,SpelNodeImpl... expressionComponents) {
+	public CompoundExpression(int pos, SpelNodeImpl... expressionComponents) {
 		super(pos, expressionComponents);
 		if (expressionComponents.length < 2) {
 			throw new IllegalStateException("Do not build compound expressions with less than two entries: " +

spring-expression/src/main/java/org/springframework/expression/spel/ast/Selection.java

@@ -61,7 +61,6 @@ public class Selection extends SpelNodeImpl {
 
 	public Selection(boolean nullSafe, int variant, int pos, SpelNodeImpl expression) {
 		super(pos, expression);
-		Assert.notNull(expression, "Expression must not be null");
 		this.nullSafe = nullSafe;
 		this.variant = variant;
 	}

spring-expression/src/main/java/org/springframework/expression/spel/ast/SpelNodeImpl.java

@@ -72,8 +72,9 @@ public abstract class SpelNodeImpl implements SpelNode, Opcodes {
 		Assert.isTrue(pos != 0, "Pos must not be 0");
 		if (!ObjectUtils.isEmpty(operands)) {
 			this.children = operands;
-			for (SpelNodeImpl childNode : operands) {
-				childNode.parent = this;
+			for (SpelNodeImpl operand : operands) {
+				Assert.notNull(operand, "Operand must not be null");
+				operand.parent = this;
 			}
 		}
 	}

spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java

@@ -329,13 +329,11 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 			if (t.kind == TokenKind.NOT) {
 				return new OperatorNot(toPos(t), expr);
 			}
-
 			if (t.kind == TokenKind.PLUS) {
 				return new OpPlus(toPos(t), expr);
 			}
 			Assert.isTrue(t.kind == TokenKind.MINUS, "Minus token expected");
 			return new OpMinus(toPos(t), expr);
-
 		}
 		if (peekToken(TokenKind.INC, TokenKind.DEC)) {
 			Token t = takeToken();
@@ -345,48 +343,40 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 			}
 			return new OpDec(toPos(t), false, expr);
 		}
-
 		return eatPrimaryExpression();
 	}
 
 	// primaryExpression : startNode (node)? -> ^(EXPRESSION startNode (node)?);
+	@Nullable
 	private SpelNodeImpl eatPrimaryExpression() {
-		List<SpelNodeImpl> nodes = new ArrayList<>();
 		SpelNodeImpl start = eatStartNode();  // always a start node
-		nodes.add(start);
-		while (maybeEatNode()) {
-			nodes.add(pop());
+		List<SpelNodeImpl> nodes = null;
+		SpelNodeImpl node = eatNode();
+		while (node != null) {
+			if (nodes == null) {
+				nodes = new ArrayList<>(4);
+				nodes.add(start);
+			}
+			nodes.add(node);
+			node = eatNode();
 		}
-		if (nodes.size() == 1) {
-			return nodes.get(0);
+		if (start == null || nodes == null) {
+			return start;
 		}
-		return new CompoundExpression(toPos((start != null ? start.getStartPosition() : 0),
+		return new CompoundExpression(toPos(start.getStartPosition(),
 				nodes.get(nodes.size() - 1).getEndPosition()),
 				nodes.toArray(new SpelNodeImpl[nodes.size()]));
 	}
 
 	// node : ((DOT dottedNode) | (SAFE_NAVI dottedNode) | nonDottedNode)+;
-	private boolean maybeEatNode() {
-		SpelNodeImpl expr = null;
-		if (peekToken(TokenKind.DOT, TokenKind.SAFE_NAVI)) {
-			expr = eatDottedNode();
-		}
-		else {
-			expr = maybeEatNonDottedNode();
-		}
-
-		if (expr == null) {
-			return false;
-		}
-		else {
-			push(expr);
-			return true;
-		}
+	@Nullable
+	private SpelNodeImpl eatNode() {
+		return (peekToken(TokenKind.DOT, TokenKind.SAFE_NAVI) ? eatDottedNode() : eatNonDottedNode());
 	}
 
 	// nonDottedNode: indexer;
 	@Nullable
-	private SpelNodeImpl maybeEatNonDottedNode() {
+	private SpelNodeImpl eatNonDottedNode() {
 		if (peekToken(TokenKind.LSQUARE)) {
 			if (maybeEatIndexer()) {
 				return pop();
@@ -404,7 +394,6 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 	//    | lastSelection
 	//    ))
 	//	;
-	@Nullable
 	private SpelNodeImpl eatDottedNode() {
 		Token t = takeToken();  // it was a '.' or a '?.'
 		boolean nullSafeNavigation = (t.kind == TokenKind.SAFE_NAVI);
@@ -414,12 +403,11 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 		}
 		if (peekToken() == null) {
 			// unexpectedly ran out of data
-			raiseInternalException(t.startPos, SpelMessage.OOD);
+			throw internalException(t.startPos, SpelMessage.OOD);
 		}
 		else {
-			raiseInternalException(t.startPos, SpelMessage.UNEXPECTED_DATA_AFTER_DOT, toString(peekToken()));
+			throw internalException(t.startPos, SpelMessage.UNEXPECTED_DATA_AFTER_DOT, toString(peekToken()));
 		}
-		return null;
 	}
 
 	// functionOrVar
@@ -479,7 +467,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 			nextToken();  // consume (first time through) or comma (subsequent times)
 			t = peekToken();
 			if (t == null) {
-				raiseInternalException(pos, SpelMessage.RUN_OUT_OF_ARGUMENTS);
+				throw internalException(pos, SpelMessage.RUN_OUT_OF_ARGUMENTS);
 			}
 			if (t.kind != TokenKind.RPAREN) {
 				accumulatedArguments.add(eatExpression());
@@ -489,7 +477,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 		while (next != null && next.kind == TokenKind.COMMA);
 
 		if (next == null) {
-			raiseInternalException(pos, SpelMessage.RUN_OUT_OF_ARGUMENTS);
+			throw internalException(pos, SpelMessage.RUN_OUT_OF_ARGUMENTS);
 		}
 	}
 
@@ -556,10 +544,8 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 				beanName = beanName.substring(1, beanName.length() - 1);
 			}
 			else {
-				raiseInternalException(beanRefToken.startPos,
-						SpelMessage.INVALID_BEAN_REFERENCE);
+				throw internalException(beanRefToken.startPos, SpelMessage.INVALID_BEAN_REFERENCE);
 			}
-
 			BeanReference beanReference;
 			if (beanRefToken.getKind() == TokenKind.FACTORY_BEAN_REF) {
 				String beanNameString = String.valueOf(TokenKind.FACTORY_BEAN_REF.tokenChars) + beanName;
@@ -692,7 +678,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 						mapElements.toArray(new SpelNodeImpl[mapElements.size()]));
 			}
 			else {
-				raiseInternalException(t.startPos, SpelMessage.OOD);
+				throw internalException(t.startPos, SpelMessage.OOD);
 			}
 		}
 		this.constructedNodes.push(expr);
@@ -721,7 +707,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 		nextToken();
 		SpelNodeImpl expr = eatExpression();
 		if (expr == null) {
-			raiseInternalException(toPos(t), SpelMessage.MISSING_SELECTION_EXPRESSION);
+			throw internalException(toPos(t), SpelMessage.MISSING_SELECTION_EXPRESSION);
 		}
 		eatToken(TokenKind.RSQUARE);
 		if (t.kind == TokenKind.SELECT_FIRST) {
@@ -752,9 +738,9 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 		}
 		if (qualifiedIdPieces.isEmpty()) {
 			if (node == null) {
-				raiseInternalException( this.expressionString.length(), SpelMessage.OOD);
+				throw internalException( this.expressionString.length(), SpelMessage.OOD);
 			}
-			raiseInternalException(node.startPos, SpelMessage.NOT_EXPECTED_TOKEN,
+			throw internalException(node.startPos, SpelMessage.NOT_EXPECTED_TOKEN,
 					"qualified ID", node.getKind().toString().toLowerCase());
 		}
 		int pos = toPos(qualifiedIdPieces.getFirst().getStartPosition(),
@@ -942,10 +928,10 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 		Token t = nextToken();
 		if (t == null) {
 			int pos = this.expressionString.length();
-			raiseInternalException(pos, SpelMessage.OOD);
+			throw internalException(pos, SpelMessage.OOD);
 		}
 		if (t.kind != expectedKind) {
-			raiseInternalException(t.startPos, SpelMessage.NOT_EXPECTED_TOKEN,
+			throw internalException(t.startPos, SpelMessage.NOT_EXPECTED_TOKEN,
 					expectedKind.toString().toLowerCase(), t.getKind().toString().toLowerCase());
 		}
 		return t;
@@ -1035,10 +1021,6 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 		return this.tokenStream.get(this.tokenStreamPointer);
 	}
 
-	private void raiseInternalException(int pos, SpelMessage message, Object... inserts) {
-		throw new InternalParseException(new SpelParseException(this.expressionString, pos, message, inserts));
-	}
-
 	public String toString(@Nullable Token t) {
 		if (t == null) {
 			return "";
@@ -1056,23 +1038,27 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 
 	private void checkLeftOperand(Token token, @Nullable SpelNodeImpl operandExpression) {
 		if (operandExpression == null) {
-			raiseInternalException(token.startPos, SpelMessage.LEFT_OPERAND_PROBLEM);
+			throw internalException(token.startPos, SpelMessage.LEFT_OPERAND_PROBLEM);
 		}
 	}
 
 	private void checkRightOperand(Token token, @Nullable SpelNodeImpl operandExpression) {
 		if (operandExpression == null) {
-			raiseInternalException(token.startPos, SpelMessage.RIGHT_OPERAND_PROBLEM);
+			throw internalException(token.startPos, SpelMessage.RIGHT_OPERAND_PROBLEM);
 		}
 	}
 
+	private InternalParseException internalException(int pos, SpelMessage message, Object... inserts) {
+		return new InternalParseException(new SpelParseException(this.expressionString, pos, message, inserts));
+	}
+
 	private int toPos(Token t) {
 		// Compress the start and end of a token into a single int
-		return (t.startPos<<16) + t.endPos;
+		return (t.startPos << 16) + t.endPos;
 	}
 
 	private int toPos(int start, int end) {
-		return (start<<16) + end;
+		return (start << 16) + end;
 	}
 
 }

spring-expression/src/test/java/org/springframework/expression/spel/standard/SpelParserTests.java

@@ -381,7 +381,6 @@ public class SpelParserTests {
 		checkNumber("22", 22, Integer.class);
 		checkNumber("+22", 22, Integer.class);
 		checkNumber("-22", -22, Integer.class);
-
 		checkNumber("2L", 2L, Long.class);
 		checkNumber("22l", 22L, Long.class);
 
@@ -392,13 +391,10 @@ public class SpelParserTests {
 
 		checkNumberError("0x", SpelMessage.NOT_AN_INTEGER);
 		checkNumberError("0xL", SpelMessage.NOT_A_LONG);
-
 		checkNumberError(".324", SpelMessage.UNEXPECTED_DATA_AFTER_DOT);
-
 		checkNumberError("3.4L", SpelMessage.REAL_CANNOT_BE_LONG);
 
 		checkNumber("3.5f", 3.5f, Float.class);
-
 		checkNumber("1.2e3", 1.2e3d, Double.class);
 		checkNumber("1.2e+3", 1.2e3d, Double.class);
 		checkNumber("1.2e-3", 1.2e-3d, Double.class);

spring-jdbc/src/main/java/org/springframework/jdbc/UncategorizedSQLException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,7 @@ package org.springframework.jdbc;
 import java.sql.SQLException;
 
 import org.springframework.dao.UncategorizedDataAccessException;
+import org.springframework.lang.Nullable;
 
 /**
  * Exception thrown when we can't classify a SQLException into
@@ -31,6 +32,7 @@ import org.springframework.dao.UncategorizedDataAccessException;
 public class UncategorizedSQLException extends UncategorizedDataAccessException {
 
 	/** SQL that led to the problem */
+	@Nullable
 	private final String sql;
 
 
@@ -40,9 +42,10 @@ public class UncategorizedSQLException extends UncategorizedDataAccessException
 	 * @param sql the offending SQL statement
 	 * @param ex the root cause
 	 */
-	public UncategorizedSQLException(String task, String sql, SQLException ex) {
-		super(task + "; uncategorized SQLException for SQL [" + sql + "]; SQL state [" +
-				ex.getSQLState() + "]; error code [" + ex.getErrorCode() + "]; " + ex.getMessage(), ex);
+	public UncategorizedSQLException(String task, @Nullable String sql, SQLException ex) {
+		super(task + "; uncategorized SQLException" + (sql != null ? " for SQL [" + sql + "]" : "") +
+				"; SQL state [" + ex.getSQLState() + "]; error code [" + ex.getErrorCode() + "]; " +
+				ex.getMessage(), ex);
 		this.sql = sql;
 	}
 
@@ -55,8 +58,9 @@ public class UncategorizedSQLException extends UncategorizedDataAccessException
 	}
 
 	/**
-	 * Return the SQL that led to the problem.
+	 * Return the SQL that led to the problem (if known).
 	 */
+	@Nullable
 	public String getSql() {
 		return this.sql;
 	}

spring-jdbc/src/main/java/org/springframework/jdbc/core/JdbcTemplate.java

@@ -41,6 +41,7 @@ import org.springframework.dao.DataAccessException;
 import org.springframework.dao.InvalidDataAccessApiUsageException;
 import org.springframework.dao.support.DataAccessUtils;
 import org.springframework.jdbc.SQLWarningException;
+import org.springframework.jdbc.UncategorizedSQLException;
 import org.springframework.jdbc.datasource.ConnectionProxy;
 import org.springframework.jdbc.datasource.DataSourceUtils;
 import org.springframework.jdbc.support.JdbcAccessor;
@@ -329,9 +330,10 @@ public class JdbcTemplate extends JdbcAccessor implements JdbcOperations {
 		catch (SQLException ex) {
 			// Release Connection early, to avoid potential connection pool deadlock
 			// in the case when the exception translator hasn't been initialized yet.
+			String sql = getSql(action);
 			DataSourceUtils.releaseConnection(con, getDataSource());
 			con = null;
-			throw getExceptionTranslator().translate("ConnectionCallback", getSql(action), ex);
+			throw translateException("ConnectionCallback", sql, ex);
 		}
 		finally {
 			DataSourceUtils.releaseConnection(con, getDataSource());
@@ -378,11 +380,12 @@ public class JdbcTemplate extends JdbcAccessor implements JdbcOperations {
 		catch (SQLException ex) {
 			// Release Connection early, to avoid potential connection pool deadlock
 			// in the case when the exception translator hasn't been initialized yet.
+			String sql = getSql(action);
 			JdbcUtils.closeStatement(stmt);
 			stmt = null;
 			DataSourceUtils.releaseConnection(con, getDataSource());
 			con = null;
-			throw getExceptionTranslator().translate("StatementCallback", getSql(action), ex);
+			throw translateException("StatementCallback", sql, ex);
 		}
 		finally {
 			JdbcUtils.closeStatement(stmt);
@@ -446,12 +449,12 @@ public class JdbcTemplate extends JdbcAccessor implements JdbcOperations {
 
 	@Override
 	public <T> List<T> query(String sql, RowMapper<T> rowMapper) throws DataAccessException {
-		return nonNull(query(sql, new RowMapperResultSetExtractor<>(rowMapper)));
+		return result(query(sql, new RowMapperResultSetExtractor<>(rowMapper)));
 	}
 
 	@Override
 	public Map<String, Object> queryForMap(String sql) throws DataAccessException {
-		return nonNull(queryForObject(sql, getColumnMapRowMapper()));
+		return result(queryForObject(sql, getColumnMapRowMapper()));
 	}
 
 	@Override
@@ -479,7 +482,7 @@ public class JdbcTemplate extends JdbcAccessor implements JdbcOperations {
 
 	@Override
 	public SqlRowSet queryForRowSet(String sql) throws DataAccessException {
-		return nonNull(query(sql, new SqlRowSetResultSetExtractor()));
+		return result(query(sql, new SqlRowSetResultSetExtractor()));
 	}
 
 	@Override
@@ -612,7 +615,7 @@ public class JdbcTemplate extends JdbcAccessor implements JdbcOperations {
 			ps = null;
 			DataSourceUtils.releaseConnection(con, getDataSource());
 			con = null;
-			throw getExceptionTranslator().translate("PreparedStatementCallback", sql, ex);
+			throw translateException("PreparedStatementCallback", sql, ex);
 		}
 		finally {
 			if (psc instanceof ParameterDisposer) {
@@ -728,27 +731,27 @@ public class JdbcTemplate extends JdbcAccessor implements JdbcOperations {
 
 	@Override
 	public <T> List<T> query(PreparedStatementCreator psc, RowMapper<T> rowMapper) throws DataAccessException {
-		return nonNull(query(psc, new RowMapperResultSetExtractor<>(rowMapper)));
+		return result(query(psc, new RowMapperResultSetExtractor<>(rowMapper)));
 	}
 
 	@Override
 	public <T> List<T> query(String sql, @Nullable PreparedStatementSetter pss, RowMapper<T> rowMapper) throws DataAccessException {
-		return nonNull(query(sql, pss, new RowMapperResultSetExtractor<>(rowMapper)));
+		return result(query(sql, pss, new RowMapperResultSetExtractor<>(rowMapper)));
 	}
 
 	@Override
 	public <T> List<T> query(String sql, Object[] args, int[] argTypes, RowMapper<T> rowMapper) throws DataAccessException {
-		return nonNull(query(sql, args, argTypes, new RowMapperResultSetExtractor<>(rowMapper)));
+		return result(query(sql, args, argTypes, new RowMapperResultSetExtractor<>(rowMapper)));
 	}
 
 	@Override
 	public <T> List<T> query(String sql, @Nullable Object[] args, RowMapper<T> rowMapper) throws DataAccessException {
-		return nonNull(query(sql, args, new RowMapperResultSetExtractor<>(rowMapper)));
+		return result(query(sql, args, new RowMapperResultSetExtractor<>(rowMapper)));
 	}
 
 	@Override
 	public <T> List<T> query(String sql, RowMapper<T> rowMapper, @Nullable Object... args) throws DataAccessException {
-		return nonNull(query(sql, args, new RowMapperResultSetExtractor<>(rowMapper)));
+		return result(query(sql, args, new RowMapperResultSetExtractor<>(rowMapper)));
 	}
 
 	@Override
@@ -794,12 +797,12 @@ public class JdbcTemplate extends JdbcAccessor implements JdbcOperations {
 
 	@Override
 	public Map<String, Object> queryForMap(String sql, Object[] args, int[] argTypes) throws DataAccessException {
-		return nonNull(queryForObject(sql, args, argTypes, getColumnMapRowMapper()));
+		return result(queryForObject(sql, args, argTypes, getColumnMapRowMapper()));
 	}
 
 	@Override
 	public Map<String, Object> queryForMap(String sql, @Nullable Object... args) throws DataAccessException {
-		return nonNull(queryForObject(sql, args, getColumnMapRowMapper()));
+		return result(queryForObject(sql, args, getColumnMapRowMapper()));
 	}
 
 	@Override
@@ -829,12 +832,12 @@ public class JdbcTemplate extends JdbcAccessor implements JdbcOperations {
 
 	@Override
 	public SqlRowSet queryForRowSet(String sql, Object[] args, int[] argTypes) throws DataAccessException {
-		return nonNull(query(sql, args, argTypes, new SqlRowSetResultSetExtractor()));
+		return result(query(sql, args, argTypes, new SqlRowSetResultSetExtractor()));
 	}
 
 	@Override
 	public SqlRowSet queryForRowSet(String sql, @Nullable Object... args) throws DataAccessException {
-		return nonNull(query(sql, args, new SqlRowSetResultSetExtractor()));
+		return result(query(sql, args, new SqlRowSetResultSetExtractor()));
 	}
 
 	protected int update(final PreparedStatementCreator psc, @Nullable final PreparedStatementSetter pss)
@@ -882,7 +885,7 @@ public class JdbcTemplate extends JdbcAccessor implements JdbcOperations {
 				try {
 					RowMapperResultSetExtractor<Map<String, Object>> rse =
 							new RowMapperResultSetExtractor<>(getColumnMapRowMapper(), 1);
-					generatedKeys.addAll(nonNull(rse.extractData(keys)));
+					generatedKeys.addAll(result(rse.extractData(keys)));
 				}
 				finally {
 					JdbcUtils.closeResultSet(keys);
@@ -1057,7 +1060,7 @@ public class JdbcTemplate extends JdbcAccessor implements JdbcOperations {
 			cs = null;
 			DataSourceUtils.releaseConnection(con, getDataSource());
 			con = null;
-			throw getExceptionTranslator().translate("CallableStatementCallback", sql, ex);
+			throw translateException("CallableStatementCallback", sql, ex);
 		}
 		finally {
 			if (csc instanceof ParameterDisposer) {
@@ -1384,6 +1387,20 @@ public class JdbcTemplate extends JdbcAccessor implements JdbcOperations {
 		}
 	}
 
+	/**
+	 * Translate the given {@link SQLException} into a generic {@link DataAccessException}.
+	 * @param task readable text describing the task being attempted
+	 * @param sql SQL query or update that caused the problem (may be {@code null})
+	 * @param ex the offending {@code SQLException}
+	 * @return a DataAccessException wrapping the {@code SQLException} (never {@code null})
+	 * @since 5.0
+	 * @see #getExceptionTranslator()
+	 */
+	protected DataAccessException translateException(String task, @Nullable String sql, SQLException ex) {
+		DataAccessException dae = getExceptionTranslator().translate(task, sql, ex);
+		return (dae != null ? dae : new UncategorizedSQLException(task, sql, ex));
+	}
+
 
 	/**
 	 * Determine SQL from potential provider object.
@@ -1401,7 +1418,7 @@ public class JdbcTemplate extends JdbcAccessor implements JdbcOperations {
 		}
 	}
 
-	private static <T> T nonNull(@Nullable T result) {
+	private static <T> T result(@Nullable T result) {
 		Assert.state(result != null, "No result");
 		return result;
 	}

spring-jdbc/src/main/java/org/springframework/jdbc/core/metadata/CallMetaDataProviderFactory.java

@@ -26,7 +26,6 @@ import org.apache.commons.logging.LogFactory;
 import org.springframework.dao.DataAccessResourceFailureException;
 import org.springframework.jdbc.support.JdbcUtils;
 import org.springframework.jdbc.support.MetaDataAccessException;
-import org.springframework.util.Assert;
 
 /**
  * Factory used to create a {@link CallMetaDataProvider} implementation
@@ -130,7 +129,6 @@ public class CallMetaDataProviderFactory {
 				}
 				return provider;
 			});
-			Assert.state(result != null, "No CallMetaDataProvider");
 			return result;
 		}
 		catch (MetaDataAccessException ex) {

spring-jdbc/src/main/java/org/springframework/jdbc/core/metadata/TableMetaDataProviderFactory.java

@@ -24,7 +24,6 @@ import org.apache.commons.logging.LogFactory;
 import org.springframework.dao.DataAccessResourceFailureException;
 import org.springframework.jdbc.support.JdbcUtils;
 import org.springframework.jdbc.support.MetaDataAccessException;
-import org.springframework.util.Assert;
 
 /**
  * Factory used to create a {@link TableMetaDataProvider} implementation
@@ -77,7 +76,6 @@ public class TableMetaDataProviderFactory {
 				}
 				return provider;
 			});
-			Assert.state(result != null, "No TableMetaDataProvider");
 			return result;
 		}
 		catch (MetaDataAccessException ex) {

spring-jdbc/src/main/java/org/springframework/jdbc/core/support/JdbcDaoSupport.java

@@ -76,6 +76,7 @@ public abstract class JdbcDaoSupport extends DaoSupport {
 	/**
 	 * Return the JDBC DataSource used by this DAO.
 	 */
+	@Nullable
 	public final DataSource getDataSource() {
 		return (this.jdbcTemplate != null ? this.jdbcTemplate.getDataSource() : null);
 	}

spring-jdbc/src/main/java/org/springframework/jdbc/support/AbstractFallbackSQLExceptionTranslator.java

@@ -23,6 +23,7 @@ import org.apache.commons.logging.LogFactory;
 
 import org.springframework.dao.DataAccessException;
 import org.springframework.jdbc.UncategorizedSQLException;
+import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
@@ -64,26 +65,26 @@ public abstract class AbstractFallbackSQLExceptionTranslator implements SQLExcep
 	 * {@link #getFallbackTranslator() fallback translator} if necessary.
 	 */
 	@Override
-	@Nullable
-	public DataAccessException translate(@Nullable String task, @Nullable String sql, SQLException ex) {
+	@NonNull
+	public DataAccessException translate(String task, @Nullable String sql, SQLException ex) {
 		Assert.notNull(ex, "Cannot translate a null SQLException");
-		if (task == null) {
-			task = "";
-		}
-		if (sql == null) {
-			sql = "";
-		}
 
-		DataAccessException dex = doTranslate(task, sql, ex);
-		if (dex != null) {
+		DataAccessException dae = doTranslate(task, sql, ex);
+		if (dae != null) {
 			// Specific exception match found.
-			return dex;
+			return dae;
 		}
+
 		// Looking for a fallback...
 		SQLExceptionTranslator fallback = getFallbackTranslator();
 		if (fallback != null) {
-			return fallback.translate(task, sql, ex);
+			dae = fallback.translate(task, sql, ex);
+			if (dae != null) {
+				// Fallback exception match found.
+				return dae;
+			}
 		}
+
 		// We couldn't identify it more precisely.
 		return new UncategorizedSQLException(task, sql, ex);
 	}
@@ -94,13 +95,13 @@ public abstract class AbstractFallbackSQLExceptionTranslator implements SQLExcep
 	 * is allowed to return {@code null} to indicate that no exception match has
 	 * been found and that fallback translation should kick in.
 	 * @param task readable text describing the task being attempted
-	 * @param sql SQL query or update that caused the problem
+	 * @param sql SQL query or update that caused the problem (if known)
 	 * @param ex the offending {@code SQLException}
 	 * @return the DataAccessException, wrapping the {@code SQLException};
 	 * or {@code null} if no exception match found
 	 */
 	@Nullable
-	protected abstract DataAccessException doTranslate(String task, String sql, SQLException ex);
+	protected abstract DataAccessException doTranslate(String task, @Nullable String sql, SQLException ex);
 
 
 	/**
@@ -112,8 +113,8 @@ public abstract class AbstractFallbackSQLExceptionTranslator implements SQLExcep
 	 * @param ex the offending {@code SQLException}
 	 * @return the message {@code String} to use
 	 */
-	protected String buildMessage(String task, String sql, SQLException ex) {
-		return task + "; SQL [" + sql + "]; " + ex.getMessage();
+	protected String buildMessage(String task, @Nullable String sql, SQLException ex) {
+		return task + "; " + (sql != null ? "SQL [" + sql : "]; " + "") + ex.getMessage();
 	}
 
 }

spring-jdbc/src/main/java/org/springframework/jdbc/support/DatabaseStartupValidator.java

@@ -97,11 +97,12 @@ public class DatabaseStartupValidator implements InitializingBean {
 	 */
 	@Override
 	public void afterPropertiesSet() {
-		if (this.dataSource == null) {
-			throw new IllegalArgumentException("dataSource is required");
+		DataSource dataSource = this.dataSource;
+		if (dataSource == null) {
+			throw new IllegalArgumentException("Property 'dataSource' is required");
 		}
 		if (this.validationQuery == null) {
-			throw new IllegalArgumentException("validationQuery is required");
+			throw new IllegalArgumentException("Property 'validationQuery' is required");
 		}
 
 		try {
@@ -114,10 +115,10 @@ public class DatabaseStartupValidator implements InitializingBean {
 				Connection con = null;
 				Statement stmt = null;
 				try {
-					con = this.dataSource.getConnection();
+					con = dataSource.getConnection();
 					if (con == null) {
 						throw new CannotGetJdbcConnectionException("Failed to execute validation query: " +
-								"DataSource returned null from getConnection(): " + this.dataSource);
+								"DataSource returned null from getConnection(): " + dataSource);
 					}
 					stmt = con.createStatement();
 					stmt.execute(this.validationQuery);

spring-jdbc/src/main/java/org/springframework/jdbc/support/JdbcUtils.java

@@ -132,6 +132,7 @@ public abstract class JdbcUtils {
 	 * @throws SQLException if thrown by the JDBC API
 	 * @see #getResultSetValue(ResultSet, int)
 	 */
+	@Nullable
 	public static Object getResultSetValue(ResultSet rs, int index, @Nullable Class<?> requiredType) throws SQLException {
 		if (requiredType == null) {
 			return getResultSetValue(rs, index);
@@ -310,7 +311,6 @@ public abstract class JdbcUtils {
 	 * the DatabaseMetaDataCallback's {@code processMetaData} method
 	 * @throws MetaDataAccessException if meta data access failed
 	 */
-	@Nullable
 	public static Object extractDatabaseMetaData(DataSource dataSource, DatabaseMetaDataCallback action)
 			throws MetaDataAccessException {
 
@@ -350,7 +350,6 @@ public abstract class JdbcUtils {
 	 * @see java.sql.DatabaseMetaData
 	 */
 	@SuppressWarnings("unchecked")
-	@Nullable
 	public static <T> T extractDatabaseMetaData(DataSource dataSource, final String metaDataMethodName)
 			throws MetaDataAccessException {
 

spring-jdbc/src/main/java/org/springframework/jdbc/support/SQLErrorCodeSQLExceptionTranslator.java

@@ -169,7 +169,7 @@ public class SQLErrorCodeSQLExceptionTranslator extends AbstractFallbackSQLExcep
 
 	@Override
 	@Nullable
-	protected DataAccessException doTranslate(String task, String sql, SQLException ex) {
+	protected DataAccessException doTranslate(String task, @Nullable String sql, SQLException ex) {
 		SQLException sqlEx = ex;
 		if (sqlEx instanceof BatchUpdateException && sqlEx.getNextException() != null) {
 			SQLException nestedSqlEx = sqlEx.getNextException();
@@ -232,11 +232,11 @@ public class SQLErrorCodeSQLExceptionTranslator extends AbstractFallbackSQLExcep
 				// Next, look for grouped error codes.
 				if (Arrays.binarySearch(this.sqlErrorCodes.getBadSqlGrammarCodes(), errorCode) >= 0) {
 					logTranslation(task, sql, sqlEx, false);
-					return new BadSqlGrammarException(task, sql, sqlEx);
+					return new BadSqlGrammarException(task, (sql != null ? sql : ""), sqlEx);
 				}
 				else if (Arrays.binarySearch(this.sqlErrorCodes.getInvalidResultSetAccessCodes(), errorCode) >= 0) {
 					logTranslation(task, sql, sqlEx, false);
-					return new InvalidResultSetAccessException(task, sql, sqlEx);
+					return new InvalidResultSetAccessException(task, (sql != null ? sql : ""), sqlEx);
 				}
 				else if (Arrays.binarySearch(this.sqlErrorCodes.getDuplicateKeyCodes(), errorCode) >= 0) {
 					logTranslation(task, sql, sqlEx, false);
@@ -397,12 +397,12 @@ public class SQLErrorCodeSQLExceptionTranslator extends AbstractFallbackSQLExcep
 		}
 	}
 
-	private void logTranslation(String task, String sql, SQLException sqlEx, boolean custom) {
+	private void logTranslation(String task, @Nullable String sql, SQLException sqlEx, boolean custom) {
 		if (logger.isDebugEnabled()) {
 			String intro = custom ? "Custom translation of" : "Translating";
 			logger.debug(intro + " SQLException with SQL state '" + sqlEx.getSQLState() +
-					"', error code '" + sqlEx.getErrorCode() + "', message [" + sqlEx.getMessage() +
-					"]; SQL was [" + sql + "] for task [" + task + "]");
+					"', error code '" + sqlEx.getErrorCode() + "', message [" + sqlEx.getMessage() + "]" +
+					(sql != null ? "; SQL was [" + sql + "]": "") + " for task [" + task + "]");
 		}
 	}
 

spring-jdbc/src/main/java/org/springframework/jdbc/support/SQLErrorCodesFactory.java

@@ -32,6 +32,7 @@ import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ConcurrentReferenceHashMap;
 import org.springframework.util.PatternMatchUtils;
+import org.springframework.util.StringUtils;
 
 /**
  * Factory for creating {@link SQLErrorCodes} based on the
@@ -211,7 +212,7 @@ public class SQLErrorCodesFactory {
 					// We could not find it - got to look it up.
 					try {
 						String name = JdbcUtils.extractDatabaseMetaData(dataSource, "getDatabaseProductName");
-						if (name != null) {
+						if (StringUtils.hasLength(name)) {
 							return registerDatabase(dataSource, name);
 						}
 					}

spring-jdbc/src/main/java/org/springframework/jdbc/support/SQLExceptionSubclassTranslator.java

@@ -64,7 +64,7 @@ public class SQLExceptionSubclassTranslator extends AbstractFallbackSQLException
 
 	@Override
 	@Nullable
-	protected DataAccessException doTranslate(String task, String sql, SQLException ex) {
+	protected DataAccessException doTranslate(String task, @Nullable String sql, SQLException ex) {
 		if (ex instanceof SQLTransientException) {
 			if (ex instanceof SQLTransientConnectionException) {
 				return new TransientDataAccessResourceException(buildMessage(task, sql, ex), ex);
@@ -90,7 +90,7 @@ public class SQLExceptionSubclassTranslator extends AbstractFallbackSQLException
 				return new PermissionDeniedDataAccessException(buildMessage(task, sql, ex), ex);
 			}
 			else if (ex instanceof SQLSyntaxErrorException) {
-				return new BadSqlGrammarException(task, sql, ex);
+				return new BadSqlGrammarException(task, (sql != null ? sql : ""), ex);
 			}
 			else if (ex instanceof SQLFeatureNotSupportedException) {
 				return new InvalidDataAccessApiUsageException(buildMessage(task, sql, ex), ex);

spring-jdbc/src/main/java/org/springframework/jdbc/support/SQLExceptionTranslator.java

@@ -46,12 +46,15 @@ public interface SQLExceptionTranslator {
 	 * check (and subsequent cast) is considered reliable when expecting JDBC-based
 	 * access to have happened.
 	 * @param task readable text describing the task being attempted
-	 * @param sql SQL query or update that caused the problem (may be {@code null})
+	 * @param sql SQL query or update that caused the problem (if known)
 	 * @param ex the offending {@code SQLException}
-	 * @return the DataAccessException, wrapping the {@code SQLException}
+	 * @return the DataAccessException wrapping the {@code SQLException},
+	 * or {@code null} if no translation could be applied
+	 * (in a custom translator; the default translators always throw an
+	 * {@link org.springframework.jdbc.UncategorizedSQLException} in such a case)
 	 * @see org.springframework.dao.DataAccessException#getRootCause()
 	 */
 	@Nullable
-	DataAccessException translate(@Nullable String task, @Nullable String sql, SQLException ex);
+	DataAccessException translate(String task, @Nullable String sql, SQLException ex);
 
 }

spring-jdbc/src/main/java/org/springframework/jdbc/support/SQLStateSQLExceptionTranslator.java

@@ -89,7 +89,7 @@ public class SQLStateSQLExceptionTranslator extends AbstractFallbackSQLException
 
 	@Override
 	@Nullable
-	protected DataAccessException doTranslate(String task, String sql, SQLException ex) {
+	protected DataAccessException doTranslate(String task, @Nullable String sql, SQLException ex) {
 		// First, the getSQLState check...
 		String sqlState = getSqlState(ex);
 		if (sqlState != null && sqlState.length() >= 2) {
@@ -98,7 +98,7 @@ public class SQLStateSQLExceptionTranslator extends AbstractFallbackSQLException
 				logger.debug("Extracted SQL state class '" + classCode + "' from value '" + sqlState + "'");
 			}
 			if (BAD_SQL_GRAMMAR_CODES.contains(classCode)) {
-				return new BadSqlGrammarException(task, sql, ex);
+				return new BadSqlGrammarException(task, (sql != null ? sql : ""), ex);
 			}
 			else if (DATA_INTEGRITY_VIOLATION_CODES.contains(classCode)) {
 				return new DataIntegrityViolationException(buildMessage(task, sql, ex), ex);

spring-jdbc/src/test/java/org/springframework/jdbc/object/StoredProcedureTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -688,14 +688,10 @@ public class StoredProcedureTests {
 			setDataSource(ds);
 			setSql(SQL);
 			getJdbcTemplate().setExceptionTranslator(new SQLExceptionTranslator() {
-
 				@Override
-				@Nullable
-				public DataAccessException translate(String task, @Nullable String sql,
-						SQLException sqlex) {
-					return new CustomDataException(sql, sqlex);
+				public DataAccessException translate(String task, @Nullable String sql, SQLException ex) {
+					return new CustomDataException(sql, ex);
 				}
-
 			});
 			compile();
 		}

spring-jdbc/src/test/java/org/springframework/jdbc/support/CustomSqlExceptionTranslator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,6 +28,7 @@ import org.springframework.lang.Nullable;
  * @author Thomas Risberg
  */
 public class CustomSqlExceptionTranslator implements SQLExceptionTranslator {
+
 	@Override
 	public DataAccessException translate(String task, @Nullable String sql, SQLException ex) {
 		if (ex.getErrorCode() == 2) {
@@ -35,4 +36,5 @@ public class CustomSqlExceptionTranslator implements SQLExceptionTranslator {
 		}
 		return null;
 	}
+
 }

spring-jms/src/main/java/org/springframework/jms/annotation/JmsListenerAnnotationBeanPostProcessor.java

@@ -345,7 +345,9 @@ public class JmsListenerAnnotationBeanPostProcessor
 
 		private MessageHandlerMethodFactory createDefaultJmsHandlerMethodFactory() {
 			DefaultMessageHandlerMethodFactory defaultFactory = new DefaultMessageHandlerMethodFactory();
-			defaultFactory.setBeanFactory(beanFactory);
+			if (beanFactory != null) {
+				defaultFactory.setBeanFactory(beanFactory);
+			}
 			defaultFactory.afterPropertiesSet();
 			return defaultFactory;
 		}

spring-jms/src/main/java/org/springframework/jms/core/support/JmsGatewaySupport.java

@@ -76,6 +76,7 @@ public abstract class JmsGatewaySupport implements InitializingBean {
 	/**
 	 * Return the JMS ConnectionFactory used by the gateway.
 	 */
+	@Nullable
 	public final ConnectionFactory getConnectionFactory() {
 		return (this.jmsTemplate != null ? this.jmsTemplate.getConnectionFactory() : null);
 	}

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/DestinationVariableMethodArgumentResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,6 +25,7 @@ import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHandlingException;
 import org.springframework.messaging.handler.annotation.DestinationVariable;
 import org.springframework.messaging.handler.annotation.ValueConstants;
+import org.springframework.util.Assert;
 
 /**
  * Resolves method parameters annotated with
@@ -52,6 +53,7 @@ public class DestinationVariableMethodArgumentResolver extends AbstractNamedValu
 	@Override
 	protected NamedValueInfo createNamedValueInfo(MethodParameter parameter) {
 		DestinationVariable annotation = parameter.getParameterAnnotation(DestinationVariable.class);
+		Assert.state(annotation != null, "No DestinationVariable annotation");
 		return new DestinationVariableNamedValueInfo(annotation);
 	}
 

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolver.java

@@ -30,6 +30,7 @@ import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHandlingException;
 import org.springframework.messaging.handler.annotation.Header;
 import org.springframework.messaging.support.NativeMessageHeaderAccessor;
+import org.springframework.util.Assert;
 
 /**
  * Resolves method parameters annotated with {@link Header @Header}.
@@ -55,6 +56,7 @@ public class HeaderMethodArgumentResolver extends AbstractNamedValueMethodArgume
 	@Override
 	protected NamedValueInfo createNamedValueInfo(MethodParameter parameter) {
 		Header annotation = parameter.getParameterAnnotation(Header.class);
+		Assert.state(annotation != null, "No Header annotation");
 		return new HeaderNamedValueInfo(annotation);
 	}
 

spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompHeaderAccessor.java

@@ -522,6 +522,7 @@ public class StompHeaderAccessor extends SimpMessageHeaderAccessor {
 		return (credentials != null ? credentials.passcode : null);
 	}
 
+	@Nullable
 	public static Integer getContentLength(Map<String, List<String>> nativeHeaders) {
 		List<String> values = nativeHeaders.get(STOMP_CONTENT_LENGTH_HEADER);
 		return (!CollectionUtils.isEmpty(values) ? Integer.valueOf(values.get(0)) : null);

spring-messaging/src/main/java/org/springframework/messaging/simp/user/DefaultUserDestinationResolver.java

@@ -161,6 +161,7 @@ public class DefaultUserDestinationResolver implements UserDestinationResolver {
 		return null;
 	}
 
+	@Nullable
 	private ParseResult parseSubscriptionMessage(Message<?> message, String sourceDestination) {
 		MessageHeaders headers = message.getHeaders();
 		String sessionId = SimpMessageHeaderAccessor.getSessionId(headers);

spring-orm/src/main/java/org/springframework/orm/jpa/EntityManagerFactoryUtils.java

@@ -17,7 +17,6 @@
 package org.springframework.orm.jpa;
 
 import java.util.Map;
-
 import javax.persistence.EntityExistsException;
 import javax.persistence.EntityManager;
 import javax.persistence.EntityManagerFactory;
@@ -481,12 +480,14 @@ public abstract class EntityManagerFactoryUtils {
 				em.flush();
 			}
 			catch (RuntimeException ex) {
+				DataAccessException dae;
 				if (this.jpaDialect != null) {
-					throw this.jpaDialect.translateExceptionIfPossible(ex);
+					dae = this.jpaDialect.translateExceptionIfPossible(ex);
 				}
 				else {
-					throw convertJpaAccessExceptionIfPossible(ex);
+					dae = convertJpaAccessExceptionIfPossible(ex);
 				}
+				throw (dae != null ? dae : ex);
 			}
 		}
 

spring-oxm/src/main/java/org/springframework/oxm/jaxb/Jaxb2Marshaller.java

@@ -490,7 +490,7 @@ public class Jaxb2Marshaller implements MimeMarshaller, MimeUnmarshaller, Generi
 			if (context == null) {
 				try {
 					if (StringUtils.hasLength(this.contextPath)) {
-						context = createJaxbContextFromContextPath();
+						context = createJaxbContextFromContextPath(this.contextPath);
 					}
 					else if (!ObjectUtils.isEmpty(this.classesToBeBound)) {
 						context = createJaxbContextFromClasses(this.classesToBeBound);
@@ -511,26 +511,26 @@ public class Jaxb2Marshaller implements MimeMarshaller, MimeUnmarshaller, Generi
 		}
 	}
 
-	private JAXBContext createJaxbContextFromContextPath() throws JAXBException {
+	private JAXBContext createJaxbContextFromContextPath(String contextPath) throws JAXBException {
 		if (logger.isInfoEnabled()) {
 			logger.info("Creating JAXBContext with context path [" + this.contextPath + "]");
 		}
 		if (this.jaxbContextProperties != null) {
 			if (this.beanClassLoader != null) {
-				return JAXBContext.newInstance(this.contextPath, this.beanClassLoader, this.jaxbContextProperties);
+				return JAXBContext.newInstance(contextPath, this.beanClassLoader, this.jaxbContextProperties);
 			}
 			else {
 				// analogous to the JAXBContext.newInstance(String) implementation
-				return JAXBContext.newInstance(this.contextPath, Thread.currentThread().getContextClassLoader(),
+				return JAXBContext.newInstance(contextPath, Thread.currentThread().getContextClassLoader(),
 						this.jaxbContextProperties);
 			}
 		}
 		else {
 			if (this.beanClassLoader != null) {
-				return JAXBContext.newInstance(this.contextPath, this.beanClassLoader);
+				return JAXBContext.newInstance(contextPath, this.beanClassLoader);
 			}
 			else {
-				return JAXBContext.newInstance(this.contextPath);
+				return JAXBContext.newInstance(contextPath);
 			}
 		}
 	}

spring-test/src/main/java/org/springframework/mock/web/MockExpressionEvaluator.java

@@ -68,7 +68,6 @@ public class MockExpressionEvaluator extends javax.servlet.jsp.el.ExpressionEval
 	public Object evaluate(String expression, Class expectedType, javax.servlet.jsp.el.VariableResolver variableResolver,
 			javax.servlet.jsp.el.FunctionMapper functionMapper) throws javax.servlet.jsp.el.ELException {
 
-		Assert.isNull(variableResolver, "Custom VariableResolver not supported");
 		return doEvaluate(expression, expectedType, functionMapper);
 	}
 
@@ -76,7 +75,6 @@ public class MockExpressionEvaluator extends javax.servlet.jsp.el.ExpressionEval
 	protected Object doEvaluate(String expression, Class expectedType, javax.servlet.jsp.el.FunctionMapper functionMapper)
 			throws javax.servlet.jsp.el.ELException {
 
-		Assert.isNull(functionMapper, "Custom FunctionMapper not supported");
 		try {
 			return ExpressionEvaluatorManager.evaluate("JSP EL expression", expression, expectedType, this.pageContext);
 		}

spring-test/src/main/java/org/springframework/test/context/jdbc/SqlScriptsTestExecutionListener.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,6 +30,7 @@ import org.springframework.core.io.ByteArrayResource;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
 import org.springframework.jdbc.datasource.init.ResourceDatabasePopulator;
+import org.springframework.lang.Nullable;
 import org.springframework.test.context.TestContext;
 import org.springframework.test.context.jdbc.Sql.ExecutionPhase;
 import org.springframework.test.context.jdbc.SqlConfig.ErrorMode;
@@ -231,6 +232,7 @@ public class SqlScriptsTestExecutionListener extends AbstractTestExecutionListen
 		}
 	}
 
+	@Nullable
 	private DataSource getDataSourceFromTransactionManager(PlatformTransactionManager transactionManager) {
 		try {
 			Method getDataSourceMethod = transactionManager.getClass().getMethod("getDataSource");

spring-test/src/main/java/org/springframework/test/context/junit/jupiter/AbstractExpressionEvaluatingCondition.java

@@ -23,7 +23,6 @@ import java.util.function.Function;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-
 import org.junit.jupiter.api.extension.ConditionEvaluationResult;
 import org.junit.jupiter.api.extension.ExecutionCondition;
 import org.junit.jupiter.api.extension.ExtensionContext;
@@ -69,7 +68,6 @@ abstract class AbstractExpressionEvaluatingCondition implements ExecutionConditi
 	/**
 	 * Evaluate the expression configured via the supplied annotation type on
 	 * the {@link AnnotatedElement} for the supplied {@link ExtensionContext}.
-	 *
 	 * @param annotationType the type of annotation to process
 	 * @param expressionExtractor a function that extracts the expression from
 	 * the annotation
@@ -88,6 +86,7 @@ abstract class AbstractExpressionEvaluatingCondition implements ExecutionConditi
 			Function<A, String> expressionExtractor, Function<A, String> reasonExtractor,
 			Function<A, Boolean> loadContextExtractor, boolean enabledOnTrue, ExtensionContext context) {
 
+		Assert.state(context.getElement().isPresent(), "No AnnotatedElement");
 		AnnotatedElement element = context.getElement().get();
 		Optional<A> annotation = findMergedAnnotation(element, annotationType);
 
@@ -100,13 +99,11 @@ abstract class AbstractExpressionEvaluatingCondition implements ExecutionConditi
 			return ConditionEvaluationResult.enabled(reason);
 		}
 
-		// @formatter:off
 		String expression = annotation.map(expressionExtractor).map(String::trim).filter(StringUtils::hasLength)
 				.orElseThrow(() -> new IllegalStateException(String.format(
 						"The expression in @%s on [%s] must not be blank", annotationType.getSimpleName(), element)));
-		// @formatter:on
 
-		boolean loadContext = annotation.map(loadContextExtractor).get();
+		boolean loadContext = loadContextExtractor.apply(annotation.get());
 		boolean evaluatedToTrue = evaluateExpression(expression, loadContext, annotationType, context);
 
 		if (evaluatedToTrue) {
@@ -127,20 +124,21 @@ abstract class AbstractExpressionEvaluatingCondition implements ExecutionConditi
 			if (logger.isDebugEnabled()) {
 				logger.debug(reason);
 			}
-			return (enabledOnTrue ? ConditionEvaluationResult.disabled(reason)
-					: ConditionEvaluationResult.enabled(reason));
+			return (enabledOnTrue ? ConditionEvaluationResult.disabled(reason) :
+					ConditionEvaluationResult.enabled(reason));
 		}
 	}
 
 	private <A extends Annotation> boolean evaluateExpression(String expression, boolean loadContext,
-			Class<A> annotationType, ExtensionContext extensionContext) {
+			Class<A> annotationType, ExtensionContext context) {
 
-		AnnotatedElement element = extensionContext.getElement().get();
+		Assert.state(context.getElement().isPresent(), "No AnnotatedElement");
+		AnnotatedElement element = context.getElement().get();
 		GenericApplicationContext gac = null;
 		ApplicationContext applicationContext;
 
 		if (loadContext) {
-			applicationContext = SpringExtension.getApplicationContext(extensionContext);
+			applicationContext = SpringExtension.getApplicationContext(context);
 		}
 		else {
 			gac = new GenericApplicationContext();
@@ -191,8 +189,9 @@ abstract class AbstractExpressionEvaluatingCondition implements ExecutionConditi
 		}
 	}
 
-	private static <A extends Annotation> Optional<A> findMergedAnnotation(AnnotatedElement element,
-			Class<A> annotationType) {
+	private static <A extends Annotation> Optional<A> findMergedAnnotation(
+			AnnotatedElement element, Class<A> annotationType) {
+
 		return Optional.ofNullable(AnnotatedElementUtils.findMergedAnnotation(element, annotationType));
 	}
 

spring-test/src/main/java/org/springframework/test/context/junit/jupiter/DisabledIfCondition.java

@@ -20,9 +20,9 @@ import org.junit.jupiter.api.extension.ConditionEvaluationResult;
 import org.junit.jupiter.api.extension.ExtensionContext;
 
 /**
- * {@code DisabledIfCondition} is an {@link ExecutionCondition} that supports the
- * {@link DisabledIf @DisabledIf} annotation when using the <em>Spring TestContext
- * Framework</em> in conjunction with JUnit 5's <em>Jupiter</em> programming model.
+ * {@code DisabledIfCondition} is an {@link org.junit.jupiter.api.extension.ExecutionCondition}
+ * that supports the {@link DisabledIf @DisabledIf} annotation when using the <em>Spring
+ * TestContext Framework</em> in conjunction with JUnit 5's <em>Jupiter</em> programming model.
  *
  * <p>Any attempt to use the {@code DisabledIfCondition} without the presence of
  * {@link DisabledIf @DisabledIf} will result in an <em>enabled</em>
@@ -43,8 +43,8 @@ public class DisabledIfCondition extends AbstractExpressionEvaluatingCondition {
 	 */
 	@Override
 	public ConditionEvaluationResult evaluateExecutionCondition(ExtensionContext context) {
-		return evaluateAnnotation(DisabledIf.class, DisabledIf::expression, DisabledIf::reason, DisabledIf::loadContext,
-			false, context);
+		return evaluateAnnotation(DisabledIf.class, DisabledIf::expression, DisabledIf::reason,
+				DisabledIf::loadContext, false, context);
 	}
 
 }

spring-test/src/main/java/org/springframework/test/context/junit/jupiter/EnabledIfCondition.java

@@ -20,9 +20,9 @@ import org.junit.jupiter.api.extension.ConditionEvaluationResult;
 import org.junit.jupiter.api.extension.ExtensionContext;
 
 /**
- * {@code EnabledIfCondition} is an {@link ExecutionCondition} that supports the
- * {@link EnabledIf @EnabledIf} annotation when using the <em>Spring TestContext
- * Framework</em> in conjunction with JUnit 5's <em>Jupiter</em> programming model.
+ * {@code EnabledIfCondition} is an {@link org.junit.jupiter.api.extension.ExecutionCondition}
+ * that supports the {@link EnabledIf @EnabledIf} annotation when using the <em>Spring
+ * TestContext Framework</em> in conjunction with JUnit 5's <em>Jupiter</em> programming model.
  *
  * <p>Any attempt to use the {@code EnabledIfCondition} without the presence of
  * {@link EnabledIf @EnabledIf} will result in an <em>enabled</em>
@@ -43,8 +43,8 @@ public class EnabledIfCondition extends AbstractExpressionEvaluatingCondition {
 	 */
 	@Override
 	public ConditionEvaluationResult evaluateExecutionCondition(ExtensionContext context) {
-		return evaluateAnnotation(EnabledIf.class, EnabledIf::expression, EnabledIf::reason, EnabledIf::loadContext,
-			true, context);
+		return evaluateAnnotation(EnabledIf.class, EnabledIf::expression, EnabledIf::reason,
+				EnabledIf::loadContext, true, context);
 	}
 
 }

spring-test/src/main/java/org/springframework/test/context/testng/AbstractTestNGSpringContextTests.java

@@ -115,7 +115,6 @@ public abstract class AbstractTestNGSpringContextTests implements IHookable, App
 	/**
 	 * Set the {@link ApplicationContext} to be used by this test instance,
 	 * provided via {@link ApplicationContextAware} semantics.
-	 *
 	 * @param applicationContext the ApplicationContext that this test runs in
 	 */
 	@Override
@@ -123,13 +122,11 @@ public abstract class AbstractTestNGSpringContextTests implements IHookable, App
 		this.applicationContext = applicationContext;
 	}
 
+
 	/**
 	 * Delegates to the configured {@link TestContextManager} to call
-	 * {@linkplain TestContextManager#beforeTestClass() 'before test class'}
-	 * callbacks.
-	 *
-	 * @throws Exception if a registered TestExecutionListener throws an
-	 * exception
+	 * {@linkplain TestContextManager#beforeTestClass() 'before test class'} callbacks.
+	 * @throws Exception if a registered TestExecutionListener throws an exception
 	 */
 	@BeforeClass(alwaysRun = true)
 	protected void springTestContextBeforeTestClass() throws Exception {
@@ -141,9 +138,7 @@ public abstract class AbstractTestNGSpringContextTests implements IHookable, App
 	 * {@linkplain TestContextManager#prepareTestInstance(Object) prepare} this test
 	 * instance prior to execution of any individual tests, for example for
 	 * injecting dependencies, etc.
-	 *
-	 * @throws Exception if a registered TestExecutionListener throws an
-	 * exception
+	 * @throws Exception if a registered TestExecutionListener throws an exception
 	 */
 	@BeforeClass(alwaysRun = true, dependsOnMethods = "springTestContextBeforeTestClass")
 	protected void springTestContextPrepareTestInstance() throws Exception {
@@ -154,7 +149,6 @@ public abstract class AbstractTestNGSpringContextTests implements IHookable, App
 	 * Delegates to the configured {@link TestContextManager} to
 	 * {@linkplain TestContextManager#beforeTestMethod(Object,Method) pre-process}
 	 * the test method before the actual test is executed.
-	 *
 	 * @param testMethod the test method which is about to be executed
 	 * @throws Exception allows all exceptions to propagate
 	 */
@@ -167,7 +161,6 @@ public abstract class AbstractTestNGSpringContextTests implements IHookable, App
 	 * Delegates to the {@linkplain IHookCallBack#runTestMethod(ITestResult) test
 	 * method} in the supplied {@code callback} to execute the actual test
 	 * and then tracks the exception thrown during test execution, if any.
-	 *
 	 * @see org.testng.IHookable#run(IHookCallBack, ITestResult)
 	 */
 	@Override
@@ -224,15 +217,14 @@ public abstract class AbstractTestNGSpringContextTests implements IHookable, App
 	/**
 	 * Delegates to the configured {@link TestContextManager} to call
 	 * {@linkplain TestContextManager#afterTestClass() 'after test class'} callbacks.
-	 *
-	 * @throws Exception if a registered TestExecutionListener throws an
-	 * exception
+	 * @throws Exception if a registered TestExecutionListener throws an exception
 	 */
 	@AfterClass(alwaysRun = true)
 	protected void springTestContextAfterTestClass() throws Exception {
 		this.testContextManager.afterTestClass();
 	}
 
+
 	private Throwable getTestResultException(ITestResult testResult) {
 		Throwable testResultException = testResult.getThrowable();
 		if (testResultException instanceof InvocationTargetException) {
@@ -241,12 +233,10 @@ public abstract class AbstractTestNGSpringContextTests implements IHookable, App
 		return testResultException;
 	}
 
-	@Nullable
 	private RuntimeException throwAsUncheckedException(Throwable t) {
 		throwAs(t);
-
 		// Appeasing the compiler: the following line will never be executed.
-		return null;
+		throw new IllegalStateException(t);
 	}
 
 	@SuppressWarnings("unchecked")

spring-test/src/main/java/org/springframework/test/web/servlet/MockMvc.java

@@ -95,7 +95,7 @@ public final class MockMvc {
 	 * A default request builder merged into every performed request.
 	 * @see org.springframework.test.web.servlet.setup.DefaultMockMvcBuilder#defaultRequest(RequestBuilder)
 	 */
-	void setDefaultRequest(RequestBuilder requestBuilder) {
+	void setDefaultRequest(@Nullable RequestBuilder requestBuilder) {
 		this.defaultRequestBuilder = requestBuilder;
 	}
 
@@ -104,7 +104,7 @@ public final class MockMvc {
 	 * @see org.springframework.test.web.servlet.setup.DefaultMockMvcBuilder#alwaysExpect(ResultMatcher)
 	 */
 	void setGlobalResultMatchers(List<ResultMatcher> resultMatchers) {
-		Assert.notNull(resultMatchers, "resultMatchers is required");
+		Assert.notNull(resultMatchers, "ResultMatcher List is required");
 		this.defaultResultMatchers = resultMatchers;
 	}
 
@@ -113,7 +113,7 @@ public final class MockMvc {
 	 * @see org.springframework.test.web.servlet.setup.DefaultMockMvcBuilder#alwaysDo(ResultHandler)
 	 */
 	void setGlobalResultHandlers(List<ResultHandler> resultHandlers) {
-		Assert.notNull(resultHandlers, "resultHandlers is required");
+		Assert.notNull(resultHandlers, "ResultHandler List is required");
 		this.defaultResultHandlers = resultHandlers;
 	}
 

spring-test/src/main/java/org/springframework/test/web/servlet/MockMvcBuilderSupport.java

@@ -41,7 +41,7 @@ import org.springframework.web.context.WebApplicationContext;
 public abstract class MockMvcBuilderSupport {
 
 	protected final MockMvc createMockMvc(Filter[] filters, MockServletConfig servletConfig,
-			WebApplicationContext webAppContext, RequestBuilder defaultRequestBuilder,
+			WebApplicationContext webAppContext, @Nullable RequestBuilder defaultRequestBuilder,
 			List<ResultMatcher> globalResultMatchers, List<ResultHandler> globalResultHandlers,
 			@Nullable List<DispatcherServletCustomizer> dispatcherServletCustomizers) {
 

spring-tx/src/main/java/org/springframework/transaction/interceptor/TransactionAspectSupport.java

@@ -448,7 +448,6 @@ public abstract class TransactionAspectSupport implements BeanFactoryAware, Init
 		if (txAttr != null && txAttr.getName() == null) {
 			txAttr = new DelegatingTransactionAttribute(txAttr) {
 				@Override
-				@Nullable
 				public String getName() {
 					return joinpointIdentification;
 				}

spring-web/spring-web.gradle

@@ -26,7 +26,7 @@ dependencies {
 	optional("javax.faces:javax.faces-api:2.2")
 	optional("javax.validation:validation-api:1.1.0.Final")
 	optional("org.codehaus.groovy:groovy-all:${groovyVersion}")
-	optional("com.caucho:hessian:4.0.38")
+	optional("com.caucho:hessian:4.0.51")
 	optional("commons-fileupload:commons-fileupload:1.3.3")
 	optional("org.synchronoss.cloud:nio-multipart-parser:1.1.0")
 	optional("io.projectreactor.ipc:reactor-netty")

spring-web/src/main/java/org/springframework/http/client/OkHttp3ClientHttpRequestFactory.java

@@ -30,6 +30,7 @@ import okhttp3.RequestBody;
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -145,6 +146,7 @@ public class OkHttp3ClientHttpRequestFactory
 		return builder.build();
 	}
 
+	@Nullable
 	private static okhttp3.MediaType getContentType(HttpHeaders headers) {
 		String rawContentType = headers.getFirst(HttpHeaders.CONTENT_TYPE);
 		return (StringUtils.hasText(rawContentType) ? okhttp3.MediaType.parse(rawContentType) : null);

spring-web/src/main/java/org/springframework/http/codec/DefaultClientCodecConfigurer.java

@@ -79,6 +79,7 @@ class DefaultClientCodecConfigurer extends AbstractCodecConfigurer implements Cl
 			return result;
 		}
 
+		@Nullable
 		private Decoder<?> getSseDecoder() {
 			if (this.sseDecoder != null) {
 				return this.sseDecoder;

spring-web/src/main/java/org/springframework/http/codec/DefaultServerCodecConfigurer.java

@@ -91,6 +91,7 @@ class DefaultServerCodecConfigurer extends AbstractCodecConfigurer implements Se
 			return result;
 		}
 
+		@Nullable
 		private Encoder<?> getSseEncoder() {
 			if (this.sseEncoder != null) {
 				return this.sseEncoder;

spring-web/src/main/java/org/springframework/http/codec/EncoderHttpMessageWriter.java

@@ -67,6 +67,7 @@ public class EncoderHttpMessageWriter<T> implements HttpMessageWriter<T> {
 		this.defaultMediaType = initDefaultMediaType(this.mediaTypes);
 	}
 
+	@Nullable
 	private static MediaType initDefaultMediaType(List<MediaType> mediaTypes) {
 		return mediaTypes.stream().filter(MediaType::isConcrete).findFirst().orElse(null);
 	}

spring-web/src/main/java/org/springframework/web/context/request/RequestContextHolder.java

@@ -145,6 +145,7 @@ public abstract class RequestContextHolder  {
  	 */
 	private static class FacesRequestAttributesFactory {
 
+		@Nullable
 		public static RequestAttributes getFacesRequestAttributes() {
 			FacesContext facesContext = FacesContext.getCurrentInstance();
 			return (facesContext != null ? new FacesRequestAttributes(facesContext) : null);

spring-web/src/main/java/org/springframework/web/multipart/commons/CommonsFileUploadSupport.java

@@ -146,6 +146,10 @@ public abstract class CommonsFileUploadSupport {
 		this.fileUpload.setHeaderEncoding(defaultEncoding);
 	}
 
+	/**
+	 * Determine the default encoding to use for parsing requests.
+	 * @see #setDefaultEncoding
+	 */
 	protected String getDefaultEncoding() {
 		String encoding = getFileUpload().getHeaderEncoding();
 		if (encoding == null) {
@@ -167,6 +171,10 @@ public abstract class CommonsFileUploadSupport {
 		this.uploadTempDirSpecified = true;
 	}
 
+	/**
+	 * Return the temporary directory where uploaded files get stored.
+	 * @see #setUploadTempDir
+	 */
 	protected boolean isUploadTempDirSpecified() {
 		return this.uploadTempDirSpecified;
 	}
@@ -247,19 +255,14 @@ public abstract class CommonsFileUploadSupport {
 			if (fileItem.isFormField()) {
 				String value;
 				String partEncoding = determineEncoding(fileItem.getContentType(), encoding);
-				if (partEncoding != null) {
-					try {
-						value = fileItem.getString(partEncoding);
-					}
-					catch (UnsupportedEncodingException ex) {
-						if (logger.isWarnEnabled()) {
-							logger.warn("Could not decode multipart item '" + fileItem.getFieldName() +
-									"' with encoding '" + partEncoding + "': using platform default");
-						}
-						value = fileItem.getString();
-					}
+				try {
+					value = fileItem.getString(partEncoding);
 				}
-				else {
+				catch (UnsupportedEncodingException ex) {
+					if (logger.isWarnEnabled()) {
+						logger.warn("Could not decode multipart item '" + fileItem.getFieldName() +
+								"' with encoding '" + partEncoding + "': using platform default");
+					}
 					value = fileItem.getString();
 				}
 				String[] curParam = multipartParameters.get(fileItem.getFieldName());
@@ -324,7 +327,6 @@ public abstract class CommonsFileUploadSupport {
 		}
 	}
 
-	@Nullable
 	private String determineEncoding(String contentTypeHeader, String defaultEncoding) {
 		if (!StringUtils.hasText(contentTypeHeader)) {
 			return defaultEncoding;

spring-web/src/main/java/org/springframework/web/util/HierarchicalUriComponents.java

@@ -28,6 +28,7 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 
+import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
@@ -135,6 +136,7 @@ final class HierarchicalUriComponents extends UriComponents {
 	}
 
 	@Override
+	@NonNull
 	public String getPath() {
 		return this.path.getPath();
 	}

spring-web/src/main/java/org/springframework/web/util/WebUtils.java

@@ -299,7 +299,6 @@ public abstract class WebUtils {
 	 * @return the value of the session attribute, or {@code null} if not found
 	 * @throws IllegalStateException if the session attribute could not be found
 	 */
-	@Nullable
 	public static Object getRequiredSessionAttribute(HttpServletRequest request, String name)
 			throws IllegalStateException {
 

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/DefaultWebClient.java

@@ -334,15 +334,12 @@ class DefaultWebClient implements WebClient {
 		}
 
 		private HttpHeaders initHeaders() {
-			if (CollectionUtils.isEmpty(defaultHeaders) && CollectionUtils.isEmpty(this.headers)) {
-				return new HttpHeaders();
+			if (CollectionUtils.isEmpty(this.headers)) {
+				return (defaultHeaders != null ? defaultHeaders : new HttpHeaders());
 			}
 			else if (CollectionUtils.isEmpty(defaultHeaders)) {
 				return this.headers;
 			}
-			else if (CollectionUtils.isEmpty(this.headers)) {
-				return defaultHeaders;
-			}
 			else {
 				HttpHeaders result = new HttpHeaders();
 				result.putAll(this.headers);
@@ -356,15 +353,12 @@ class DefaultWebClient implements WebClient {
 		}
 
 		private MultiValueMap<String, String> initCookies() {
-			if (CollectionUtils.isEmpty(defaultCookies) && CollectionUtils.isEmpty(this.cookies)) {
-				return new LinkedMultiValueMap<>(0);
+			if (CollectionUtils.isEmpty(this.cookies)) {
+				return (defaultCookies != null ? defaultCookies : new LinkedMultiValueMap<>(0));
 			}
 			else if (CollectionUtils.isEmpty(defaultCookies)) {
 				return this.cookies;
 			}
-			else if (CollectionUtils.isEmpty(this.cookies)) {
-				return defaultCookies;
-			}
 			else {
 				MultiValueMap<String, String> result = new LinkedMultiValueMap<>();
 				result.putAll(this.cookies);
@@ -379,9 +373,11 @@ class DefaultWebClient implements WebClient {
 		}
 	}
 
+
 	private static class DefaultResponseSpec implements ResponseSpec {
 
-		private static final StatusHandler DEFAULT_STATUS_HANDLER = new StatusHandler(HttpStatus::isError, DefaultResponseSpec::createResponseException);
+		private static final StatusHandler DEFAULT_STATUS_HANDLER =
+				new StatusHandler(HttpStatus::isError, DefaultResponseSpec::createResponseException);
 
 		private final Mono<ClientResponse> responseMono;
 

spring-webflux/src/main/java/org/springframework/web/reactive/result/condition/CompositeRequestCondition.java

@@ -50,7 +50,7 @@ public class CompositeRequestCondition extends AbstractRequestCondition<Composit
 	 * same number of conditions so they may be compared and combined.
 	 * It is acceptable to provide {@code null} conditions.
 	 */
-	public CompositeRequestCondition(@Nullable RequestCondition<?>... requestConditions) {
+	public CompositeRequestCondition(RequestCondition<?>... requestConditions) {
 		this.requestConditions = wrap(requestConditions);
 	}
 

spring-webflux/src/main/java/org/springframework/web/reactive/result/condition/RequestConditionHolder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -38,12 +38,13 @@ import org.springframework.web.server.ServerWebExchange;
  */
 public final class RequestConditionHolder extends AbstractRequestCondition<RequestConditionHolder> {
 
+	@Nullable
 	private final RequestCondition<Object> condition;
 
 
 	/**
 	 * Create a new holder to wrap the given request condition.
-	 * @param requestCondition the condition to hold, may be {@code null}
+	 * @param requestCondition the condition to hold (may be {@code null})
 	 */
 	@SuppressWarnings("unchecked")
 	public RequestConditionHolder(@Nullable RequestCondition<?> requestCondition) {
@@ -86,23 +87,12 @@ public final class RequestConditionHolder extends AbstractRequestCondition<Reque
 			return this;
 		}
 		else {
-			assertEqualConditionTypes(other);
+			assertEqualConditionTypes(this.condition, other.condition);
 			RequestCondition<?> combined = (RequestCondition<?>) this.condition.combine(other.condition);
 			return new RequestConditionHolder(combined);
 		}
 	}
 
-	/**
-	 * Ensure the held request conditions are of the same type.
-	 */
-	private void assertEqualConditionTypes(RequestConditionHolder other) {
-		Class<?> clazz = this.condition.getClass();
-		Class<?> otherClazz = other.condition.getClass();
-		if (!clazz.equals(otherClazz)) {
-			throw new ClassCastException("Incompatible request conditions: " + clazz + " and " + otherClazz);
-		}
-	}
-
 	/**
 	 * Get the matching condition for the held request condition wrap it in a
 	 * new RequestConditionHolder instance. Or otherwise if this is an empty
@@ -134,9 +124,20 @@ public final class RequestConditionHolder extends AbstractRequestCondition<Reque
 			return -1;
 		}
 		else {
-			assertEqualConditionTypes(other);
+			assertEqualConditionTypes(this.condition, other.condition);
 			return this.condition.compareTo(other.condition, exchange);
 		}
 	}
 
+	/**
+	 * Ensure the held request conditions are of the same type.
+	 */
+	private void assertEqualConditionTypes(RequestCondition<?> cond1, RequestCondition<?> cond2) {
+		Class<?> clazz = cond1.getClass();
+		Class<?> otherClazz = cond2.getClass();
+		if (!clazz.equals(otherClazz)) {
+			throw new ClassCastException("Incompatible request conditions: " + clazz + " vs " + otherClazz);
+		}
+	}
+
 }

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/RequestMappingHandlerMapping.java

@@ -124,6 +124,7 @@ public class RequestMappingHandlerMapping extends RequestMappingInfoHandlerMappi
 	 * @see #getCustomTypeCondition(Class)
 	 * @see #getCustomMethodCondition(Method)
 	 */
+	@Nullable
 	private RequestMappingInfo createRequestMappingInfo(AnnotatedElement element) {
 		RequestMapping requestMapping = AnnotatedElementUtils.findMergedAnnotation(element, RequestMapping.class);
 		RequestCondition<?> condition = (element instanceof Class ?

spring-webmvc/src/main/java/org/springframework/web/servlet/config/AnnotationDrivenBeanDefinitionParser.java

@@ -467,6 +467,7 @@ class AnnotationDrivenBeanDefinitionParser implements BeanDefinitionParser {
 		}
 	}
 
+	@Nullable
 	private String getAsyncTimeout(Element element) {
 		Element asyncElement = DomUtils.getChildElementByTagName(element, "async-support");
 		return (asyncElement != null) ? asyncElement.getAttribute("default-timeout") : null;
@@ -555,6 +556,7 @@ class AnnotationDrivenBeanDefinitionParser implements BeanDefinitionParser {
 		return result;
 	}
 
+	@Nullable
 	private ManagedList<?> getReturnValueHandlers(Element element, ParserContext parserContext) {
 		Element handlers = DomUtils.getChildElementByTagName(element, "return-value-handlers");
 		return (handlers != null ? extractBeanSubElements(handlers, parserContext) : null);

spring-webmvc/src/main/java/org/springframework/web/servlet/config/ResourcesBeanDefinitionParser.java

@@ -154,6 +154,7 @@ class ResourcesBeanDefinitionParser implements BeanDefinitionParser {
 		}
 	}
 
+	@Nullable
 	private String registerResourceHandler(ParserContext parserContext, Element element, @Nullable Object source) {
 		String locationAttr = element.getAttribute("location");
 		if (!StringUtils.hasText(locationAttr)) {

spring-webmvc/src/main/java/org/springframework/web/servlet/config/ViewResolversBeanDefinitionParser.java

@@ -123,19 +123,19 @@ public class ViewResolversBeanDefinitionParser implements BeanDefinitionParser {
 		compositeResolverBeanDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
 
 		names = new String[] {"content-negotiation"};
-		List<Element> contentnNegotiationElements = DomUtils.getChildElementsByTagName(element, names);
-		if (contentnNegotiationElements.isEmpty()) {
+		List<Element> contentNegotiationElements = DomUtils.getChildElementsByTagName(element, names);
+		if (contentNegotiationElements.isEmpty()) {
 			compositeResolverBeanDef.getPropertyValues().add("viewResolvers", resolvers);
 		}
-		else if (contentnNegotiationElements.size() == 1) {
-			BeanDefinition beanDef = createContentNegotiatingViewResolver(contentnNegotiationElements.get(0), context);
+		else if (contentNegotiationElements.size() == 1) {
+			BeanDefinition beanDef = createContentNegotiatingViewResolver(contentNegotiationElements.get(0), context);
 			beanDef.getPropertyValues().add("viewResolvers", resolvers);
 			ManagedList<Object> list = new ManagedList<>(1);
 			list.add(beanDef);
 			compositeResolverBeanDef.getPropertyValues().add("order", Ordered.HIGHEST_PRECEDENCE);
 			compositeResolverBeanDef.getPropertyValues().add("viewResolvers", list);
 		}
-		else if (contentnNegotiationElements.size() > 1) {
+		else {
 			throw new IllegalArgumentException("Only one <content-negotiation> element is allowed.");
 		}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/PatternsRequestCondition.java

@@ -232,6 +232,7 @@ public final class PatternsRequestCondition extends AbstractRequestCondition<Pat
 		return matches;
 	}
 
+	@Nullable
 	private String getMatchingPattern(String pattern, String lookupPath) {
 		if (pattern.equals(lookupPath)) {
 			return pattern;

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/RequestMethodsRequestCondition.java

@@ -130,6 +130,7 @@ public final class RequestMethodsRequestCondition extends AbstractRequestConditi
 		return matchRequestMethod(expectedMethod);
 	}
 
+	@Nullable
 	private RequestMethodsRequestCondition matchRequestMethod(String httpMethodValue) {
 		HttpMethod httpMethod = HttpMethod.resolve(httpMethodValue);
 		if (httpMethod != null) {

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/RequestMappingInfo.java

@@ -189,6 +189,7 @@ public final class RequestMappingInfo implements RequestCondition<RequestMapping
 				methods, params, headers, consumes, produces, custom.getCondition());
 	}
 
+	@Nullable
 	private String combineNames(RequestMappingInfo other) {
 		if (this.name != null && other.name != null) {
 			String separator = RequestMappingInfoHandlerMethodMappingNamingStrategy.SEPARATOR;

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilder.java

@@ -552,6 +552,7 @@ public class MvcUriComponentsBuilder {
 		}
 	}
 
+	@Nullable
 	private static WebApplicationContext getWebApplicationContext() {
 		RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
 		if (requestAttributes == null) {

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/DefaultResourceResolverChain.java

@@ -81,6 +81,7 @@ class DefaultResourceResolverChain implements ResourceResolverChain {
 		}
 	}
 
+	@Nullable
 	private ResourceResolver getNext() {
 		Assert.state(this.index <= this.resolvers.size(),
 				"Current index exceeds the number of configured ResourceResolvers");

spring-webmvc/src/main/java/org/springframework/web/servlet/support/JspAwareRequestContext.java

@@ -111,11 +111,13 @@ public class JspAwareRequestContext extends RequestContext {
 	 */
 	private static class JstlPageLocaleResolver {
 
+		@Nullable
 		public static Locale getJstlLocale(PageContext pageContext) {
 			Object localeObject = Config.find(pageContext, Config.FMT_LOCALE);
 			return (localeObject instanceof Locale ? (Locale) localeObject : null);
 		}
 
+		@Nullable
 		public static TimeZone getJstlTimeZone(PageContext pageContext) {
 			Object timeZoneObject = Config.find(pageContext, Config.FMT_TIME_ZONE);
 			return (timeZoneObject instanceof TimeZone ? (TimeZone) timeZoneObject : null);

spring-webmvc/src/main/java/org/springframework/web/servlet/support/RequestContext.java

@@ -904,6 +904,7 @@ public class RequestContext {
 	 */
 	private static class JstlLocaleResolver {
 
+		@Nullable
 		public static Locale getJstlLocale(HttpServletRequest request, @Nullable ServletContext servletContext) {
 			Object localeObject = Config.get(request, Config.FMT_LOCALE);
 			if (localeObject == null) {
@@ -918,6 +919,7 @@ public class RequestContext {
 			return (localeObject instanceof Locale ? (Locale) localeObject : null);
 		}
 
+		@Nullable
 		public static TimeZone getJstlTimeZone(HttpServletRequest request, @Nullable ServletContext servletContext) {
 			Object timeZoneObject = Config.get(request, Config.FMT_TIME_ZONE);
 			if (timeZoneObject == null) {

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/EvalTag.java

@@ -198,6 +198,7 @@ public class EvalTag extends HtmlEscapingAwareTag {
 			throw new UnsupportedOperationException();
 		}
 
+		@Nullable
 		private Object resolveImplicitVariable(String name) throws AccessException {
 			if (this.variableResolver == null) {
 				return null;

spring-websocket/src/main/java/org/springframework/web/socket/messaging/SubProtocolWebSocketHandler.java

@@ -411,6 +411,7 @@ public class SubProtocolWebSocketHandler
 		return handler;
 	}
 
+	@Nullable
 	private String resolveSessionId(Message<?> message) {
 		for (SubProtocolHandler handler : this.protocolHandlerLookup.values()) {
 			String sessionId = handler.resolveSessionId(message);

spring-websocket/src/main/java/org/springframework/web/socket/server/standard/SpringConfigurator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,6 +26,7 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
 import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.lang.Nullable;
 import org.springframework.stereotype.Component;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
@@ -97,6 +98,7 @@ public class SpringConfigurator extends Configurator {
 		return wac.getAutowireCapableBeanFactory().createBean(endpointClass);
 	}
 
+	@Nullable
 	private String getBeanNameByType(WebApplicationContext wac, Class<?> endpointClass) {
 		String wacId = wac.getId();