Add metadata support for immutable ConfigurationProperties type

Closes gh-16071

spring-boot-project/spring-boot-docs/src/main/asciidoc/appendix/configuration-metadata.adoc

@@ -809,8 +809,11 @@ is used to populate the `description` attribute.
 NOTE: You should only use simple text with `@ConfigurationProperties` field Javadoc, since
 they are not processed before being added to the JSON.
 
-Properties are discovered through the presence of standard getters and setters with
-special handling for collection types (that is detected even if only a getter is present).
+If the class has a single constructor with at least one parameters, one property is
+created per constructor parameter. Otherwise, properties are discovered through the
+presence of standard getters and setters with special handling for collection types (that
+is detected even if only a getter is present).
+
 The annotation processor also supports the use of the `@Data`, `@Getter`, and `@Setter`
 lombok annotations.
 

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/ConfigurationMetadataAnnotationProcessor.java

@@ -73,6 +73,9 @@ public class ConfigurationMetadataAnnotationProcessor extends AbstractProcessor
 	static final String DEPRECATED_CONFIGURATION_PROPERTY_ANNOTATION = "org.springframework.boot."
 			+ "context.properties.DeprecatedConfigurationProperty";
 
+	static final String DEFAULT_VALUE_ANNOTATION = "org.springframework.boot."
+			+ "context.properties.bind.DefaultValue";
+
 	static final String ENDPOINT_ANNOTATION = "org.springframework.boot.actuate."
 			+ "endpoint.annotation.Endpoint";
 
@@ -100,6 +103,10 @@ public class ConfigurationMetadataAnnotationProcessor extends AbstractProcessor
 		return DEPRECATED_CONFIGURATION_PROPERTY_ANNOTATION;
 	}
 
+	protected String defaultValueAnnotation() {
+		return DEFAULT_VALUE_ANNOTATION;
+	}
+
 	protected String endpointAnnotation() {
 		return ENDPOINT_ANNOTATION;
 	}
@@ -127,8 +134,8 @@ public class ConfigurationMetadataAnnotationProcessor extends AbstractProcessor
 		this.metadataEnv = new MetadataGenerationEnvironment(env,
 				configurationPropertiesAnnotation(),
 				nestedConfigurationPropertyAnnotation(),
-				deprecatedConfigurationPropertyAnnotation(), endpointAnnotation(),
-				readOperationAnnotation());
+				deprecatedConfigurationPropertyAnnotation(), defaultValueAnnotation(),
+				endpointAnnotation(), readOperationAnnotation());
 	}
 
 	@Override

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/ConstructorParameterPropertyDescriptor.java

@@ -0,0 +1,224 @@
+/*
+ * Copyright 2012-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationprocessor;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+import javax.lang.model.element.AnnotationMirror;
+import javax.lang.model.element.Element;
+import javax.lang.model.element.ExecutableElement;
+import javax.lang.model.element.TypeElement;
+import javax.lang.model.element.VariableElement;
+import javax.lang.model.type.PrimitiveType;
+import javax.lang.model.type.TypeMirror;
+import javax.lang.model.util.TypeKindVisitor8;
+import javax.tools.Diagnostic.Kind;
+
+/**
+ * A {@link PropertyDescriptor} for a constructor parameter.
+ *
+ * @author Stephane Nicoll
+ */
+class ConstructorParameterPropertyDescriptor extends PropertyDescriptor<VariableElement> {
+
+	ConstructorParameterPropertyDescriptor(TypeElement ownerElement,
+			ExecutableElement factoryMethod, VariableElement source, String name,
+			TypeMirror type, VariableElement field, ExecutableElement getter,
+			ExecutableElement setter) {
+		super(ownerElement, factoryMethod, source, name, type, field, getter, setter);
+	}
+
+	@Override
+	protected boolean isProperty(MetadataGenerationEnvironment env) {
+		// If it's a constructor parameter, it doesn't matter as we must be able to bind
+		// it to build the object.
+		return !isNested(env);
+	}
+
+	@Override
+	protected Object resolveDefaultValue(MetadataGenerationEnvironment environment) {
+		Object defaultValue = getDefaultValueFromAnnotation(environment, getSource());
+		if (defaultValue != null) {
+			return defaultValue;
+		}
+		return getSource().asType().accept(DefaultPrimitiveTypeVisitor.INSTANCE, null);
+	}
+
+	private Object getDefaultValueFromAnnotation(
+			MetadataGenerationEnvironment environment, Element element) {
+		AnnotationMirror defaultValueAnnotation = environment
+				.getDefaultValueAnnotation(element);
+		if (defaultValueAnnotation != null) {
+			List<String> defaultValue = (List<String>) environment
+					.getAnnotationElementValues(defaultValueAnnotation).get("value");
+			if (defaultValue != null) {
+				try {
+					TypeMirror specificType = determineSpecificType(environment);
+					if (defaultValue.size() == 1) {
+						return coerceValue(specificType, defaultValue.get(0));
+					}
+					return defaultValue.stream()
+							.map((value) -> coerceValue(specificType, value))
+							.collect(Collectors.toList());
+				}
+				catch (IllegalArgumentException ex) {
+					environment.getMessager().printMessage(Kind.ERROR, ex.getMessage(),
+							element, defaultValueAnnotation);
+				}
+			}
+		}
+		return null;
+	}
+
+	private TypeMirror determineSpecificType(MetadataGenerationEnvironment environment) {
+		TypeMirror candidate = getSource().asType();
+		TypeMirror elementCandidate = environment.getTypeUtils()
+				.extractElementType(candidate);
+		if (elementCandidate != null) {
+			candidate = elementCandidate;
+		}
+		PrimitiveType primitiveType = environment.getTypeUtils()
+				.getPrimitiveType(candidate);
+		return (primitiveType != null) ? primitiveType : candidate;
+	}
+
+	private Object coerceValue(TypeMirror type, String value) {
+		Object coercedValue = type.accept(DefaultValueCoercionTypeVisitor.INSTANCE,
+				value);
+		return (coercedValue != null) ? coercedValue : value;
+	}
+
+	private static class DefaultValueCoercionTypeVisitor
+			extends TypeKindVisitor8<Object, String> {
+
+		private static final DefaultValueCoercionTypeVisitor INSTANCE = new DefaultValueCoercionTypeVisitor();
+
+		private Integer parseInteger(String value) {
+			try {
+				return Integer.valueOf(value);
+			}
+			catch (NumberFormatException ex) {
+				throw new IllegalArgumentException(
+						String.format("Invalid number representation '%s'", value));
+			}
+		}
+
+		private Double parseFloatingPoint(String value) {
+			try {
+				return Double.valueOf(value);
+			}
+			catch (NumberFormatException ex) {
+				throw new IllegalArgumentException(String
+						.format("Invalid floating point representation '%s'", value));
+			}
+		}
+
+		@Override
+		public Object visitPrimitiveAsBoolean(PrimitiveType t, String value) {
+			return Boolean.parseBoolean(value);
+		}
+
+		@Override
+		public Object visitPrimitiveAsByte(PrimitiveType t, String value) {
+			return parseInteger(value);
+		}
+
+		@Override
+		public Object visitPrimitiveAsShort(PrimitiveType t, String value) {
+			return parseInteger(value);
+		}
+
+		@Override
+		public Object visitPrimitiveAsInt(PrimitiveType t, String value) {
+			return parseInteger(value);
+		}
+
+		@Override
+		public Object visitPrimitiveAsLong(PrimitiveType t, String value) {
+			return parseInteger(value);
+		}
+
+		@Override
+		public Object visitPrimitiveAsChar(PrimitiveType t, String value) {
+			if (value.length() > 1) {
+				throw new IllegalArgumentException(
+						String.format("Invalid character representation '%s'", value));
+			}
+			return value;
+		}
+
+		@Override
+		public Object visitPrimitiveAsFloat(PrimitiveType t, String value) {
+			return parseFloatingPoint(value);
+		}
+
+		@Override
+		public Object visitPrimitiveAsDouble(PrimitiveType t, String value) {
+			return parseFloatingPoint(value);
+		}
+
+	}
+
+	private static class DefaultPrimitiveTypeVisitor
+			extends TypeKindVisitor8<Object, Void> {
+
+		private static final DefaultPrimitiveTypeVisitor INSTANCE = new DefaultPrimitiveTypeVisitor();
+
+		@Override
+		public Object visitPrimitiveAsBoolean(PrimitiveType t, Void ignore) {
+			return false;
+		}
+
+		@Override
+		public Object visitPrimitiveAsByte(PrimitiveType t, Void ignore) {
+			return 0;
+		}
+
+		@Override
+		public Object visitPrimitiveAsShort(PrimitiveType t, Void ignore) {
+			return 0;
+		}
+
+		@Override
+		public Object visitPrimitiveAsInt(PrimitiveType t, Void ignore) {
+			return 0;
+		}
+
+		@Override
+		public Object visitPrimitiveAsLong(PrimitiveType t, Void ignore) {
+			return 0L;
+		}
+
+		@Override
+		public Object visitPrimitiveAsChar(PrimitiveType t, Void ignore) {
+			return null;
+		}
+
+		@Override
+		public Object visitPrimitiveAsFloat(PrimitiveType t, Void ignore) {
+			return 0;
+		}
+
+		@Override
+		public Object visitPrimitiveAsDouble(PrimitiveType t, Void ignore) {
+			return 0D;
+		}
+
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/JavaBeanPropertyDescriptor.java

@@ -41,4 +41,9 @@ class JavaBeanPropertyDescriptor extends PropertyDescriptor<ExecutableElement> {
 				&& (getSetter() != null || isCollection);
 	}
 
+	@Override
+	protected Object resolveDefaultValue(MetadataGenerationEnvironment environment) {
+		return environment.getFieldDefaultValue(getOwnerElement(), getName());
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/LombokPropertyDescriptor.java

@@ -57,6 +57,11 @@ class LombokPropertyDescriptor extends PropertyDescriptor<VariableElement> {
 		return !env.isExcluded(getType()) && (hasSetter(env) || isCollection);
 	}
 
+	@Override
+	protected Object resolveDefaultValue(MetadataGenerationEnvironment environment) {
+		return environment.getFieldDefaultValue(getOwnerElement(), getName());
+	}
+
 	@Override
 	protected boolean isNested(MetadataGenerationEnvironment environment) {
 		if (!hasLombokPublicAccessor(environment, true)) {

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/MetadataGenerationEnvironment.java

@@ -16,14 +16,18 @@
 
 package org.springframework.boot.configurationprocessor;
 
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
+import javax.annotation.processing.Messager;
 import javax.annotation.processing.ProcessingEnvironment;
 import javax.lang.model.element.AnnotationMirror;
+import javax.lang.model.element.AnnotationValue;
 import javax.lang.model.element.Element;
 import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.element.TypeElement;
@@ -51,6 +55,8 @@ class MetadataGenerationEnvironment {
 
 	private final Elements elements;
 
+	private final Messager messager;
+
 	private final FieldValuesParser fieldValuesParser;
 
 	private final Map<TypeElement, Map<String, Object>> defaultValues = new HashMap<>();
@@ -61,6 +67,8 @@ class MetadataGenerationEnvironment {
 
 	private final String deprecatedConfigurationPropertyAnnotation;
 
+	private final String defaultValueAnnotation;
+
 	private final String endpointAnnotation;
 
 	private final String readOperationAnnotation;
@@ -68,15 +76,18 @@ class MetadataGenerationEnvironment {
 	MetadataGenerationEnvironment(ProcessingEnvironment environment,
 			String configurationPropertiesAnnotation,
 			String nestedConfigurationPropertyAnnotation,
-			String deprecatedConfigurationPropertyAnnotation, String endpointAnnotation,
+			String deprecatedConfigurationPropertyAnnotation,
+			String defaultValueAnnotation, String endpointAnnotation,
 			String readOperationAnnotation) {
 		this.typeExcludes = determineTypeExcludes();
 		this.typeUtils = new TypeUtils(environment);
 		this.elements = environment.getElementUtils();
+		this.messager = environment.getMessager();
 		this.fieldValuesParser = resolveFieldValuesParser(environment);
 		this.configurationPropertiesAnnotation = configurationPropertiesAnnotation;
 		this.nestedConfigurationPropertyAnnotation = nestedConfigurationPropertyAnnotation;
 		this.deprecatedConfigurationPropertyAnnotation = deprecatedConfigurationPropertyAnnotation;
+		this.defaultValueAnnotation = defaultValueAnnotation;
 		this.endpointAnnotation = endpointAnnotation;
 		this.readOperationAnnotation = readOperationAnnotation;
 	}
@@ -112,7 +123,18 @@ class MetadataGenerationEnvironment {
 		return this.typeUtils;
 	}
 
-	public Object getDefaultValue(TypeElement type, String name) {
+	public Messager getMessager() {
+		return this.messager;
+	}
+
+	/**
+	 * Return the default value of the field with the specified {@code name}.
+	 * @param type the type to consider
+	 * @param name the name of the field
+	 * @return the default value or {@code null} if the field does not exist or no default
+	 * value has been detected
+	 */
+	public Object getFieldDefaultValue(TypeElement type, String name) {
 		return this.defaultValues.computeIfAbsent(type, this::resolveFieldValues)
 				.get(name);
 	}
@@ -171,10 +193,21 @@ class MetadataGenerationEnvironment {
 	public Map<String, Object> getAnnotationElementValues(AnnotationMirror annotation) {
 		Map<String, Object> values = new LinkedHashMap<>();
 		annotation.getElementValues().forEach((name, value) -> values
-				.put(name.getSimpleName().toString(), value.getValue()));
+				.put(name.getSimpleName().toString(), getAnnotationValue(value)));
 		return values;
 	}
 
+	private Object getAnnotationValue(AnnotationValue annotationValue) {
+		Object value = annotationValue.getValue();
+		if (value instanceof List) {
+			List<Object> values = new ArrayList<>();
+			((List<?>) value)
+					.forEach((v) -> values.add(((AnnotationValue) v).getValue()));
+			return values;
+		}
+		return value;
+	}
+
 	public TypeElement getConfigurationPropertiesAnnotationElement() {
 		return this.elements.getTypeElement(this.configurationPropertiesAnnotation);
 	}
@@ -187,6 +220,10 @@ class MetadataGenerationEnvironment {
 		return getAnnotation(element, this.nestedConfigurationPropertyAnnotation);
 	}
 
+	public AnnotationMirror getDefaultValueAnnotation(Element element) {
+		return getAnnotation(element, this.defaultValueAnnotation);
+	}
+
 	public TypeElement getEndpointAnnotationElement() {
 		return this.elements.getTypeElement(this.endpointAnnotation);
 	}

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/PropertyDescriptor.java

@@ -33,7 +33,7 @@ import org.springframework.boot.configurationprocessor.metadata.ItemMetadata;
  * @param <S> the type of the source element that determines the property
  * @author Stephane Nicoll
  */
-abstract class PropertyDescriptor<S> {
+abstract class PropertyDescriptor<S extends Element> {
 
 	private final TypeElement ownerElement;
 
@@ -98,6 +98,9 @@ abstract class PropertyDescriptor<S> {
 
 	protected abstract boolean isProperty(MetadataGenerationEnvironment environment);
 
+	protected abstract Object resolveDefaultValue(
+			MetadataGenerationEnvironment environment);
+
 	protected ItemDeprecation resolveItemDeprecation(
 			MetadataGenerationEnvironment environment) {
 		boolean deprecated = environment.isDeprecated(getGetter())
@@ -164,10 +167,6 @@ abstract class PropertyDescriptor<S> {
 		return environment.getTypeUtils().getJavaDoc(getField());
 	}
 
-	private Object resolveDefaultValue(MetadataGenerationEnvironment environment) {
-		return environment.getDefaultValue(getOwnerElement(), getName());
-	}
-
 	private boolean isCyclePresent(Element returnType, Element element) {
 		if (!(element.getEnclosingElement() instanceof TypeElement)) {
 			return false;

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/PropertyDescriptorResolver.java

@@ -16,13 +16,16 @@
 
 package org.springframework.boot.configurationprocessor;
 
-import java.util.ArrayList;
+import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.stream.Stream;
 
 import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.element.TypeElement;
+import javax.lang.model.element.VariableElement;
 import javax.lang.model.type.TypeMirror;
+import javax.lang.model.util.ElementFilter;
 
 /**
  * Resolve {@link PropertyDescriptor} instances.
@@ -49,23 +52,59 @@ class PropertyDescriptorResolver {
 	public Stream<PropertyDescriptor<?>> resolve(TypeElement type,
 			ExecutableElement factoryMethod) {
 		TypeElementMembers members = new TypeElementMembers(this.environment, type);
-		List<PropertyDescriptor<?>> candidates = new ArrayList<>();
+		ExecutableElement constructor = resolveConstructor(type);
+		if (constructor != null) {
+			return resolveConstructorProperties(type, factoryMethod, members,
+					constructor);
+		}
+		else {
+			return resolveJavaBeanProperties(type, factoryMethod, members);
+		}
+	}
+
+	public Stream<PropertyDescriptor<?>> resolveConstructorProperties(TypeElement type,
+			ExecutableElement factoryMethod, TypeElementMembers members,
+			ExecutableElement constructor) {
+		Map<String, PropertyDescriptor<?>> candidates = new LinkedHashMap<>();
+		constructor.getParameters().forEach((parameter) -> {
+			String name = parameter.getSimpleName().toString();
+			TypeMirror propertyType = parameter.asType();
+			ExecutableElement getter = members.getPublicGetter(name, propertyType);
+			ExecutableElement setter = members.getPublicSetter(name, propertyType);
+			VariableElement field = members.getFields().get(name);
+			register(candidates, new ConstructorParameterPropertyDescriptor(type,
+					factoryMethod, parameter, name, propertyType, field, getter, setter));
+		});
+		return candidates.values().stream();
+	}
+
+	public Stream<PropertyDescriptor<?>> resolveJavaBeanProperties(TypeElement type,
+			ExecutableElement factoryMethod, TypeElementMembers members) {
 		// First check if we have regular java bean properties there
+		Map<String, PropertyDescriptor<?>> candidates = new LinkedHashMap<>();
 		members.getPublicGetters().forEach((name, getter) -> {
-			TypeMirror returnType = getter.getReturnType();
-			candidates.add(new JavaBeanPropertyDescriptor(type, factoryMethod, getter,
-					name, returnType, members.getFields().get(name),
-					members.getPublicSetter(name, returnType)));
+			TypeMirror propertyType = getter.getReturnType();
+			register(candidates,
+					new JavaBeanPropertyDescriptor(type, factoryMethod, getter, name,
+							propertyType, members.getFields().get(name),
+							members.getPublicSetter(name, propertyType)));
 		});
 		// Then check for Lombok ones
 		members.getFields().forEach((name, field) -> {
-			TypeMirror returnType = field.asType();
-			ExecutableElement getter = members.getPublicGetter(name, returnType);
-			ExecutableElement setter = members.getPublicSetter(name, returnType);
-			candidates.add(new LombokPropertyDescriptor(type, factoryMethod, field, name,
-					returnType, getter, setter));
+			TypeMirror propertyType = field.asType();
+			ExecutableElement getter = members.getPublicGetter(name, propertyType);
+			ExecutableElement setter = members.getPublicSetter(name, propertyType);
+			register(candidates, new LombokPropertyDescriptor(type, factoryMethod, field,
+					name, propertyType, getter, setter));
 		});
-		return candidates.stream().filter(this::isCandidate);
+		return candidates.values().stream();
+	}
+
+	private void register(Map<String, PropertyDescriptor<?>> candidates,
+			PropertyDescriptor<?> descriptor) {
+		if (!candidates.containsKey(descriptor.getName()) && isCandidate(descriptor)) {
+			candidates.put(descriptor.getName(), descriptor);
+		}
 	}
 
 	private boolean isCandidate(PropertyDescriptor<?> descriptor) {
@@ -73,4 +112,13 @@ class PropertyDescriptorResolver {
 				|| descriptor.isNested(this.environment);
 	}
 
+	private ExecutableElement resolveConstructor(TypeElement type) {
+		List<ExecutableElement> constructors = ElementFilter
+				.constructorsIn(type.getEnclosedElements());
+		if (constructors.size() == 1 && constructors.get(0).getParameters().size() > 0) {
+			return constructors.get(0);
+		}
+		return null;
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/TypeUtils.java

@@ -142,6 +142,42 @@ class TypeUtils {
 		return type.accept(this.typeExtractor, createTypeDescriptor(element));
 	}
 
+	/**
+	 * Extract the target element type from the specified container type or {@code null}
+	 * if no element type was found.
+	 * @param type a type, potentially wrapping an element type
+	 * @return the element type or {@code null} if no specific type was found
+	 */
+	public TypeMirror extractElementType(TypeMirror type) {
+		if (!this.env.getTypeUtils().isAssignable(type, this.collectionType)) {
+			return null;
+		}
+		return getCollectionElementType(type);
+	}
+
+	private TypeMirror getCollectionElementType(TypeMirror type) {
+		if (((TypeElement) this.types.asElement(type)).getQualifiedName()
+				.contentEquals(Collection.class.getName())) {
+			DeclaredType declaredType = (DeclaredType) type;
+			// raw type, just "Collection"
+			if (declaredType.getTypeArguments().size() == 0) {
+				return this.types.getDeclaredType(this.env.getElementUtils()
+						.getTypeElement(Object.class.getName()));
+			}
+			else { // return type argument to Collection<...>
+				return declaredType.getTypeArguments().get(0);
+			}
+		}
+
+		// recursively walk the supertypes, looking for Collection<...>
+		for (TypeMirror superType : this.env.getTypeUtils().directSupertypes(type)) {
+			if (this.types.isAssignable(superType, this.collectionType)) {
+				return getCollectionElementType(superType);
+			}
+		}
+		return null;
+	}
+
 	public boolean isCollectionOrMap(TypeMirror type) {
 		return this.env.getTypeUtils().isAssignable(type, this.collectionType)
 				|| this.env.getTypeUtils().isAssignable(type, this.mapType);
@@ -156,6 +192,19 @@ class TypeUtils {
 		return "".equals(javadoc) ? null : javadoc;
 	}
 
+	/**
+	 * Return the {@link PrimitiveType} of the specified type or {@code null} if the type
+	 * does not represent a valid wrapper type.
+	 * @param typeMirror a type
+	 * @return the primitive type or {@code null} if the type is not a wrapper type
+	 */
+	public PrimitiveType getPrimitiveType(TypeMirror typeMirror) {
+		if (getPrimitiveFor(typeMirror) != null) {
+			return this.types.unboxedType(typeMirror);
+		}
+		return null;
+	}
+
 	public TypeMirror getWrapperOrPrimitiveFor(TypeMirror typeMirror) {
 		Class<?> candidate = getWrapperFor(typeMirror);
 		if (candidate != null) {

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/ConfigurationMetadataAnnotationProcessorTests.java

@@ -43,6 +43,9 @@ import org.springframework.boot.configurationsample.specific.InnerClassHierarchi
 import org.springframework.boot.configurationsample.specific.InnerClassProperties;
 import org.springframework.boot.configurationsample.specific.InnerClassRootConfig;
 import org.springframework.boot.configurationsample.specific.InvalidAccessorProperties;
+import org.springframework.boot.configurationsample.specific.InvalidDefaultValueCharacterProperties;
+import org.springframework.boot.configurationsample.specific.InvalidDefaultValueFloatingPointProperties;
+import org.springframework.boot.configurationsample.specific.InvalidDefaultValueNumberProperties;
 import org.springframework.boot.configurationsample.specific.InvalidDoubleRegistrationProperties;
 import org.springframework.boot.configurationsample.specific.SimplePojo;
 import org.springframework.boot.configurationsample.specific.StaticAccessor;
@@ -385,4 +388,26 @@ public class ConfigurationMetadataAnnotationProcessorTests
 				.withMessageContaining("Compilation failed");
 	}
 
+	@Test
+	public void constructorParameterPropertyWithInvalidDefaultValueOnNumber() {
+		assertThatIllegalStateException()
+				.isThrownBy(() -> compile(InvalidDefaultValueNumberProperties.class))
+				.withMessageContaining("Compilation failed");
+	}
+
+	@Test
+	public void constructorParameterPropertyWithInvalidDefaultValueOnFloatingPoint() {
+		assertThatIllegalStateException()
+				.isThrownBy(
+						() -> compile(InvalidDefaultValueFloatingPointProperties.class))
+				.withMessageContaining("Compilation failed");
+	}
+
+	@Test
+	public void constructorParameterPropertyWithInvalidDefaultValueOnCharacter() {
+		assertThatIllegalStateException()
+				.isThrownBy(() -> compile(InvalidDefaultValueCharacterProperties.class))
+				.withMessageContaining("Compilation failed");
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/ConstructorParameterPropertyDescriptorTests.java

@@ -0,0 +1,318 @@
+/*
+ * Copyright 2012-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationprocessor;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import javax.lang.model.element.ExecutableElement;
+import javax.lang.model.element.TypeElement;
+import javax.lang.model.element.VariableElement;
+import javax.lang.model.util.ElementFilter;
+
+import org.junit.Test;
+
+import org.springframework.boot.configurationsample.immutable.ImmutableCollectionProperties;
+import org.springframework.boot.configurationsample.immutable.ImmutableInnerClassProperties;
+import org.springframework.boot.configurationsample.immutable.ImmutablePrimitiveProperties;
+import org.springframework.boot.configurationsample.immutable.ImmutablePrimitiveWithDefaultsProperties;
+import org.springframework.boot.configurationsample.immutable.ImmutablePrimitiveWrapperWithDefaultsProperties;
+import org.springframework.boot.configurationsample.immutable.ImmutableSimpleProperties;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link ConstructorParameterPropertyDescriptor}.
+ *
+ * @author Stephane Nicoll
+ */
+public class ConstructorParameterPropertyDescriptorTests extends PropertyDescriptorTests {
+
+	@Test
+	public void constructorParameterSimpleProperty() throws IOException {
+		process(ImmutableSimpleProperties.class, (roundEnv, metadataEnv) -> {
+			TypeElement ownerElement = roundEnv
+					.getRootElement(ImmutableSimpleProperties.class);
+			ConstructorParameterPropertyDescriptor property = createPropertyDescriptor(
+					ownerElement, "theName");
+			assertThat(property.getName()).isEqualTo("theName");
+			assertThat(property.getSource()).hasToString("theName");
+			assertThat(property.getGetter().getSimpleName()).hasToString("getTheName");
+			assertThat(property.isProperty(metadataEnv)).isTrue();
+			assertThat(property.isNested(metadataEnv)).isFalse();
+		});
+	}
+
+	@Test
+	public void constructorParameterNestedPropertySameClass() throws IOException {
+		process(ImmutableInnerClassProperties.class, (roundEnv, metadataEnv) -> {
+			TypeElement ownerElement = roundEnv
+					.getRootElement(ImmutableInnerClassProperties.class);
+			ConstructorParameterPropertyDescriptor property = createPropertyDescriptor(
+					ownerElement, "first");
+			assertThat(property.getName()).isEqualTo("first");
+			assertThat(property.getSource()).hasToString("first");
+			assertThat(property.getGetter().getSimpleName()).hasToString("getFirst");
+			assertThat(property.isProperty(metadataEnv)).isFalse();
+			assertThat(property.isNested(metadataEnv)).isTrue();
+		});
+	}
+
+	@Test
+	public void constructorParameterNestedPropertyWithAnnotation() throws IOException {
+		process(ImmutableInnerClassProperties.class, (roundEnv, metadataEnv) -> {
+			TypeElement ownerElement = roundEnv
+					.getRootElement(ImmutableInnerClassProperties.class);
+			ConstructorParameterPropertyDescriptor property = createPropertyDescriptor(
+					ownerElement, "third");
+			assertThat(property.getName()).isEqualTo("third");
+			assertThat(property.getSource()).hasToString("third");
+			assertThat(property.getGetter().getSimpleName()).hasToString("getThird");
+			assertThat(property.isProperty(metadataEnv)).isFalse();
+			assertThat(property.isNested(metadataEnv)).isTrue();
+		});
+	}
+
+	@Test
+	public void constructorParameterSimplePropertyWithNoAccessorShouldBeExposed()
+			throws IOException {
+		process(ImmutableSimpleProperties.class, (roundEnv, metadataEnv) -> {
+			TypeElement ownerElement = roundEnv
+					.getRootElement(ImmutableSimpleProperties.class);
+			ConstructorParameterPropertyDescriptor property = createPropertyDescriptor(
+					ownerElement, "counter");
+			assertThat(property.getName()).isEqualTo("counter");
+			assertThat(property.getSource()).hasToString("counter");
+			assertThat(property.getGetter()).isNull();
+			assertThat(property.isProperty(metadataEnv)).isTrue();
+			assertThat(property.isNested(metadataEnv)).isFalse();
+		});
+	}
+
+	@Test
+	public void constructorParameterMetadataSimpleProperty() throws IOException {
+		process(ImmutableSimpleProperties.class, (roundEnv, metadataEnv) -> {
+			TypeElement ownerElement = roundEnv
+					.getRootElement(ImmutableSimpleProperties.class);
+			ConstructorParameterPropertyDescriptor property = createPropertyDescriptor(
+					ownerElement, "counter");
+			assertItemMetadata(metadataEnv, property).isProperty().hasName("test.counter")
+					.hasType(Long.class).hasSourceType(ImmutableSimpleProperties.class)
+					.hasNoDescription().isNotDeprecated();
+		});
+	}
+
+	@Test
+	public void constructorParameterMetadataNestedGroup() throws IOException {
+		process(ImmutableInnerClassProperties.class, (roundEnv, metadataEnv) -> {
+			TypeElement ownerElement = roundEnv
+					.getRootElement(ImmutableInnerClassProperties.class);
+			ConstructorParameterPropertyDescriptor property = createPropertyDescriptor(
+					ownerElement, "first");
+			assertItemMetadata(metadataEnv, property).isGroup().hasName("test.first")
+					.hasType(
+							"org.springframework.boot.configurationsample.immutable.ImmutableInnerClassProperties$Foo")
+					.hasSourceType(ImmutableInnerClassProperties.class)
+					.hasSourceMethod("getFirst()").hasNoDescription().isNotDeprecated();
+		});
+	}
+
+	@Test
+	public void constructorParameterDeprecatedPropertyOnGetter() throws IOException {
+		process(ImmutableSimpleProperties.class, (roundEnv, metadataEnv) -> {
+			TypeElement ownerElement = roundEnv
+					.getRootElement(ImmutableSimpleProperties.class);
+			ExecutableElement getter = getMethod(ownerElement, "isFlag");
+			VariableElement field = getField(ownerElement, "flag");
+			VariableElement constructorParameter = getConstructorParameter(ownerElement,
+					"flag");
+			ConstructorParameterPropertyDescriptor property = new ConstructorParameterPropertyDescriptor(
+					ownerElement, null, constructorParameter, "flag", field.asType(),
+					field, getter, null);
+			assertItemMetadata(metadataEnv, property).isProperty()
+					.isDeprecatedWithNoInformation();
+		});
+	}
+
+	@Test
+	public void constructorParameterPropertyWithDescription() throws IOException {
+		process(ImmutableSimpleProperties.class, (roundEnv, metadataEnv) -> {
+			TypeElement ownerElement = roundEnv
+					.getRootElement(ImmutableSimpleProperties.class);
+			ConstructorParameterPropertyDescriptor property = createPropertyDescriptor(
+					ownerElement, "theName");
+			assertItemMetadata(metadataEnv, property).isProperty()
+					.hasDescription("The name of this simple properties.");
+		});
+	}
+
+	@Test
+	public void constructorParameterPropertyWithDefaultValue() throws IOException {
+		process(ImmutableSimpleProperties.class, (roundEnv, metadataEnv) -> {
+			TypeElement ownerElement = roundEnv
+					.getRootElement(ImmutableSimpleProperties.class);
+			ConstructorParameterPropertyDescriptor property = createPropertyDescriptor(
+					ownerElement, "theName");
+			assertItemMetadata(metadataEnv, property).isProperty()
+					.hasDefaultValue("boot");
+		});
+	}
+
+	@Test
+	public void constructorParameterPropertyWithPrimitiveTypes() throws IOException {
+		process(ImmutablePrimitiveProperties.class, (roundEnv, metadataEnv) -> {
+			TypeElement ownerElement = roundEnv
+					.getRootElement(ImmutablePrimitiveProperties.class);
+			assertItemMetadata(metadataEnv,
+					createPropertyDescriptor(ownerElement, "flag"))
+							.hasDefaultValue(false);
+			assertItemMetadata(metadataEnv,
+					createPropertyDescriptor(ownerElement, "octet")).hasDefaultValue(0);
+			assertItemMetadata(metadataEnv,
+					createPropertyDescriptor(ownerElement, "letter"))
+							.hasDefaultValue(null);
+			assertItemMetadata(metadataEnv,
+					createPropertyDescriptor(ownerElement, "number")).hasDefaultValue(0);
+			assertItemMetadata(metadataEnv,
+					createPropertyDescriptor(ownerElement, "counter")).hasDefaultValue(0);
+			assertItemMetadata(metadataEnv,
+					createPropertyDescriptor(ownerElement, "value")).hasDefaultValue(0L);
+			assertItemMetadata(metadataEnv,
+					createPropertyDescriptor(ownerElement, "percentage"))
+							.hasDefaultValue(0);
+			assertItemMetadata(metadataEnv,
+					createPropertyDescriptor(ownerElement, "ratio")).hasDefaultValue(0D);
+		});
+	}
+
+	@Test
+	public void constructorParameterPropertyWithPrimitiveTypesAndDefaultValues()
+			throws IOException {
+		process(ImmutablePrimitiveWithDefaultsProperties.class,
+				(roundEnv, metadataEnv) -> {
+					TypeElement ownerElement = roundEnv.getRootElement(
+							ImmutablePrimitiveWithDefaultsProperties.class);
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "flag"))
+									.hasDefaultValue(true);
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "octet"))
+									.hasDefaultValue(120);
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "letter"))
+									.hasDefaultValue("a");
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "number"))
+									.hasDefaultValue(1000);
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "counter"))
+									.hasDefaultValue(42);
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "value"))
+									.hasDefaultValue(2000);
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "percentage"))
+									.hasDefaultValue(0.5);
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "ratio"))
+									.hasDefaultValue(42.42);
+				});
+	}
+
+	@Test
+	public void constructorParameterPropertyWithPrimitiveWrapperTypesAndDefaultValues()
+			throws IOException {
+		process(ImmutablePrimitiveWrapperWithDefaultsProperties.class,
+				(roundEnv, metadataEnv) -> {
+					TypeElement ownerElement = roundEnv.getRootElement(
+							ImmutablePrimitiveWrapperWithDefaultsProperties.class);
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "flag"))
+									.hasDefaultValue(true);
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "octet"))
+									.hasDefaultValue(120);
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "letter"))
+									.hasDefaultValue("a");
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "number"))
+									.hasDefaultValue(1000);
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "counter"))
+									.hasDefaultValue(42);
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "value"))
+									.hasDefaultValue(2000);
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "percentage"))
+									.hasDefaultValue(0.5);
+					assertItemMetadata(metadataEnv,
+							createPropertyDescriptor(ownerElement, "ratio"))
+									.hasDefaultValue(42.42);
+				});
+	}
+
+	@Test
+	public void constructorParameterPropertyWithCollectionTypesAndDefaultValues()
+			throws IOException {
+		process(ImmutableCollectionProperties.class, (roundEnv, metadataEnv) -> {
+			TypeElement ownerElement = roundEnv
+					.getRootElement(ImmutableCollectionProperties.class);
+			assertItemMetadata(metadataEnv,
+					createPropertyDescriptor(ownerElement, "names"))
+							.hasDefaultValue(null);
+			assertItemMetadata(metadataEnv,
+					createPropertyDescriptor(ownerElement, "flags"))
+							.hasDefaultValue(Arrays.asList(true, false));
+			assertItemMetadata(metadataEnv,
+					createPropertyDescriptor(ownerElement, "durations"))
+							.hasDefaultValue(Arrays.asList("10s", "1m", "1h"));
+		});
+	}
+
+	protected ConstructorParameterPropertyDescriptor createPropertyDescriptor(
+			TypeElement ownerElement, String name) {
+		VariableElement constructorParameter = getConstructorParameter(ownerElement,
+				name);
+		VariableElement field = getField(ownerElement, name);
+		ExecutableElement getter = getMethod(ownerElement,
+				createAccessorMethodName("get", name));
+		ExecutableElement setter = getMethod(ownerElement,
+				createAccessorMethodName("set", name));
+		return new ConstructorParameterPropertyDescriptor(ownerElement, null,
+				constructorParameter, name, field.asType(), field, getter, setter);
+	}
+
+	private VariableElement getConstructorParameter(TypeElement ownerElement,
+			String name) {
+		List<ExecutableElement> constructors = ElementFilter
+				.constructorsIn(ownerElement.getEnclosedElements()).stream()
+				.filter((constructor) -> !constructor.getParameters().isEmpty())
+				.collect(Collectors.toList());
+		if (constructors.size() != 1) {
+			throw new IllegalStateException(
+					"No candidate constructor for " + ownerElement);
+		}
+		return constructors.get(0).getParameters().stream()
+				.filter((parameter) -> parameter.getSimpleName().toString().equals(name))
+				.findFirst().orElse(null);
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/ImmutablePropertiesMetadataGenerationTests.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2012-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationprocessor;
+
+import org.junit.Test;
+
+import org.springframework.boot.configurationprocessor.metadata.ConfigurationMetadata;
+import org.springframework.boot.configurationprocessor.metadata.Metadata;
+import org.springframework.boot.configurationsample.immutable.ImmutableSimpleProperties;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Metadata generation tests for immutable properties.
+ *
+ * @author Stephane Nicoll
+ */
+public class ImmutablePropertiesMetadataGenerationTests
+		extends AbstractMetadataGenerationTests {
+
+	@Test
+	public void immutableSimpleProperties() {
+		ConfigurationMetadata metadata = compile(ImmutableSimpleProperties.class);
+		assertThat(metadata).has(Metadata.withGroup("immutable")
+				.fromSource(ImmutableSimpleProperties.class));
+		assertThat(metadata).has(Metadata.withProperty("immutable.the-name", String.class)
+				.fromSource(ImmutableSimpleProperties.class)
+				.withDescription("The name of this simple properties.")
+				.withDefaultValue("boot"));
+		assertThat(metadata).has(Metadata.withProperty("immutable.flag", Boolean.class)
+				.withDefaultValue(false).fromSource(ImmutableSimpleProperties.class)
+				.withDescription("A simple flag.").withDeprecation(null, null));
+		assertThat(metadata).has(Metadata.withProperty("immutable.comparator"));
+		assertThat(metadata).has(Metadata.withProperty("immutable.counter"));
+		assertThat(metadata.getItems()).hasSize(5);
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/MetadataGenerationEnvironmentFactory.java

@@ -36,6 +36,7 @@ class MetadataGenerationEnvironmentFactory
 				TestConfigurationMetadataAnnotationProcessor.CONFIGURATION_PROPERTIES_ANNOTATION,
 				TestConfigurationMetadataAnnotationProcessor.NESTED_CONFIGURATION_PROPERTY_ANNOTATION,
 				TestConfigurationMetadataAnnotationProcessor.DEPRECATED_CONFIGURATION_PROPERTY_ANNOTATION,
+				TestConfigurationMetadataAnnotationProcessor.DEFAULT_VALUE_ANNOTATION,
 				TestConfigurationMetadataAnnotationProcessor.ENDPOINT_ANNOTATION,
 				TestConfigurationMetadataAnnotationProcessor.READ_OPERATION_ANNOTATION);
 	}

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/PropertyDescriptorResolverTests.java

@@ -34,6 +34,7 @@ import org.junit.rules.TemporaryFolder;
 import org.springframework.boot.configurationprocessor.metadata.ItemMetadata;
 import org.springframework.boot.configurationprocessor.test.RoundEnvironmentTester;
 import org.springframework.boot.configurationprocessor.test.TestableAnnotationProcessor;
+import org.springframework.boot.configurationsample.immutable.ImmutableSimpleProperties;
 import org.springframework.boot.configurationsample.lombok.LombokExplicitProperties;
 import org.springframework.boot.configurationsample.lombok.LombokSimpleDataProperties;
 import org.springframework.boot.configurationsample.lombok.LombokSimpleProperties;
@@ -41,6 +42,7 @@ import org.springframework.boot.configurationsample.simple.HierarchicalPropertie
 import org.springframework.boot.configurationsample.simple.HierarchicalPropertiesGrandparent;
 import org.springframework.boot.configurationsample.simple.HierarchicalPropertiesParent;
 import org.springframework.boot.configurationsample.simple.SimpleProperties;
+import org.springframework.boot.configurationsample.specific.TwoConstructorsExample;
 import org.springframework.boot.testsupport.compiler.TestCompiler;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -100,6 +102,21 @@ public class PropertyDescriptorResolverTests {
 						"description", "counter", "number", "items")));
 	}
 
+	@Test
+	public void propertiesWithConstructorParameters() throws IOException {
+		process(ImmutableSimpleProperties.class,
+				propertyNames((stream) -> assertThat(stream).containsExactly("theName",
+						"flag", "comparator", "counter")));
+	}
+
+	@Test
+	public void propertiesWithSeveralConstructors() throws IOException {
+		process(TwoConstructorsExample.class,
+				propertyNames((stream) -> assertThat(stream).containsExactly("name")));
+		process(TwoConstructorsExample.class, properties((stream) -> assertThat(stream)
+				.element(0).isInstanceOf(JavaBeanPropertyDescriptor.class)));
+	}
+
 	private BiConsumer<TypeElement, MetadataGenerationEnvironment> properties(
 			Consumer<Stream<PropertyDescriptor<?>>> stream) {
 		return (element, metadataEnv) -> {

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/test/TestConfigurationMetadataAnnotationProcessor.java

@@ -47,6 +47,8 @@ public class TestConfigurationMetadataAnnotationProcessor
 
 	public static final String DEPRECATED_CONFIGURATION_PROPERTY_ANNOTATION = "org.springframework.boot.configurationsample.DeprecatedConfigurationProperty";
 
+	public static final String DEFAULT_VALUE_ANNOTATION = "org.springframework.boot.configurationsample.DefaultValue";
+
 	public static final String ENDPOINT_ANNOTATION = "org.springframework.boot.configurationsample.Endpoint";
 
 	public static final String READ_OPERATION_ANNOTATION = "org.springframework.boot.configurationsample.ReadOperation";
@@ -74,6 +76,11 @@ public class TestConfigurationMetadataAnnotationProcessor
 		return DEPRECATED_CONFIGURATION_PROPERTY_ANNOTATION;
 	}
 
+	@Override
+	protected String defaultValueAnnotation() {
+		return DEFAULT_VALUE_ANNOTATION;
+	}
+
 	@Override
 	protected String endpointAnnotation() {
 		return ENDPOINT_ANNOTATION;

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/DefaultValue.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2012-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationsample;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Alternative to Spring Boot's {@code @DefaultValue} for testing (removes the need for a
+ * dependency on the real annotation).
+ *
+ * @author Stephane Nicoll
+ */
+@Target({ ElementType.PARAMETER })
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface DefaultValue {
+
+	String[] value();
+
+}

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/immutable/ImmutableCollectionProperties.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2012-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationsample.immutable;
+
+import java.time.Duration;
+import java.util.List;
+
+import org.springframework.boot.configurationsample.DefaultValue;
+
+/**
+ * Simple immutable properties with collections types and defaults.
+ *
+ * @author Stephane Nicoll
+ */
+public class ImmutableCollectionProperties {
+
+	private final List<String> names;
+
+	private final List<Boolean> flags;
+
+	private final List<Duration> durations;
+
+	public ImmutableCollectionProperties(List<String> names,
+			@DefaultValue({ "true", "false" }) List<Boolean> flags,
+			@DefaultValue({ "10s", "1m", "1h" }) List<Duration> durations) {
+		this.names = names;
+		this.flags = flags;
+		this.durations = durations;
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/immutable/ImmutableInnerClassProperties.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright 2012-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationsample.immutable;
+
+import org.springframework.boot.configurationsample.NestedConfigurationProperty;
+import org.springframework.boot.configurationsample.specific.SimplePojo;
+
+/**
+ * Inner properties, in immutable format.
+ *
+ * @author Stephane Nicoll
+ */
+public class ImmutableInnerClassProperties {
+
+	private final Foo first;
+
+	private Foo second;
+
+	@NestedConfigurationProperty
+	private final SimplePojo third;
+
+	private final Fourth fourth;
+
+	public ImmutableInnerClassProperties(Foo first, Foo second, SimplePojo third,
+			Fourth fourth) {
+		this.first = first;
+		this.second = second;
+		this.third = third;
+		this.fourth = fourth;
+	}
+
+	public Foo getFirst() {
+		return this.first;
+	}
+
+	public Foo getTheSecond() {
+		return this.second;
+	}
+
+	public void setTheSecond(Foo second) {
+		this.second = second;
+	}
+
+	public SimplePojo getThird() {
+		return this.third;
+	}
+
+	public Fourth getFourth() {
+		return this.fourth;
+	}
+
+	public static class Foo {
+
+		private String name;
+
+		private final Bar bar = new Bar();
+
+		public String getName() {
+			return this.name;
+		}
+
+		public void setName(String name) {
+			this.name = name;
+		}
+
+		public Bar getBar() {
+			return this.bar;
+		}
+
+		public static class Bar {
+
+			private String name;
+
+			public String getName() {
+				return this.name;
+			}
+
+			public void setName(String name) {
+				this.name = name;
+			}
+
+		}
+
+	}
+
+	public enum Fourth {
+
+		YES, NO
+
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/immutable/ImmutablePrimitiveProperties.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2012-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationsample.immutable;
+
+/**
+ * Simple immutable properties with primitive types.
+ *
+ * @author Stephane Nicoll
+ */
+@SuppressWarnings("unused")
+public class ImmutablePrimitiveProperties {
+
+	private final boolean flag;
+
+	private final byte octet;
+
+	private final char letter;
+
+	private final short number;
+
+	private final int counter;
+
+	private final long value;
+
+	private final float percentage;
+
+	private final double ratio;
+
+	public ImmutablePrimitiveProperties(boolean flag, byte octet, char letter,
+			short number, int counter, long value, float percentage, double ratio) {
+		this.flag = flag;
+		this.octet = octet;
+		this.letter = letter;
+		this.number = number;
+		this.counter = counter;
+		this.value = value;
+		this.percentage = percentage;
+		this.ratio = ratio;
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/immutable/ImmutablePrimitiveWithDefaultsProperties.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2012-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationsample.immutable;
+
+import org.springframework.boot.configurationsample.DefaultValue;
+
+/**
+ * Simple immutable properties with primitive types and defaults.
+ *
+ * @author Stephane Nicoll
+ */
+@SuppressWarnings("unused")
+public class ImmutablePrimitiveWithDefaultsProperties {
+
+	private final boolean flag;
+
+	private final byte octet;
+
+	private final char letter;
+
+	private final short number;
+
+	private final int counter;
+
+	private final long value;
+
+	private final float percentage;
+
+	private final double ratio;
+
+	public ImmutablePrimitiveWithDefaultsProperties(@DefaultValue("true") boolean flag,
+			@DefaultValue("120") byte octet, @DefaultValue("a") char letter,
+			@DefaultValue("1000") short number, @DefaultValue("42") int counter,
+			@DefaultValue("2000") long value, @DefaultValue("0.5") float percentage,
+			@DefaultValue("42.42") double ratio) {
+		this.flag = flag;
+		this.octet = octet;
+		this.letter = letter;
+		this.number = number;
+		this.counter = counter;
+		this.value = value;
+		this.percentage = percentage;
+		this.ratio = ratio;
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/immutable/ImmutablePrimitiveWrapperWithDefaultsProperties.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2012-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationsample.immutable;
+
+import org.springframework.boot.configurationsample.DefaultValue;
+
+/**
+ * Simple immutable properties with primitive wrapper types and defaults.
+ *
+ * @author Stephane Nicoll
+ */
+@SuppressWarnings("unused")
+public class ImmutablePrimitiveWrapperWithDefaultsProperties {
+
+	private final Boolean flag;
+
+	private final Byte octet;
+
+	private final Character letter;
+
+	private final Short number;
+
+	private final Integer counter;
+
+	private final Long value;
+
+	private final Float percentage;
+
+	private final Double ratio;
+
+	public ImmutablePrimitiveWrapperWithDefaultsProperties(
+			@DefaultValue("true") Boolean flag, @DefaultValue("120") Byte octet,
+			@DefaultValue("a") Character letter, @DefaultValue("1000") Short number,
+			@DefaultValue("42") Integer counter, @DefaultValue("2000") Long value,
+			@DefaultValue("0.5") Float percentage, @DefaultValue("42.42") Double ratio) {
+		this.flag = flag;
+		this.octet = octet;
+		this.letter = letter;
+		this.number = number;
+		this.counter = counter;
+		this.value = value;
+		this.percentage = percentage;
+		this.ratio = ratio;
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/immutable/ImmutableSimpleProperties.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2012-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationsample.immutable;
+
+import java.util.Comparator;
+
+import org.springframework.boot.configurationsample.ConfigurationProperties;
+import org.springframework.boot.configurationsample.DefaultValue;
+
+/**
+ * Simple properties, in immutable format.
+ *
+ * @author Stephane Nicoll
+ */
+@ConfigurationProperties("immutable")
+public class ImmutableSimpleProperties {
+
+	/**
+	 * The name of this simple properties.
+	 */
+	private final String theName;
+
+	/**
+	 * A simple flag.
+	 */
+	private final boolean flag;
+
+	// An interface can still be injected because it might have a converter
+	private final Comparator<?> comparator;
+
+	// Even if it is not exposed, we're still offering a way to bind the value via the
+	// constructor so it should be present in the metadata
+	@SuppressWarnings("unused")
+	private final Long counter;
+
+	public ImmutableSimpleProperties(@DefaultValue("boot") String theName, boolean flag,
+			Comparator<?> comparator, Long counter) {
+		this.theName = theName;
+		this.flag = flag;
+		this.comparator = comparator;
+		this.counter = counter;
+	}
+
+	public String getTheName() {
+		return this.theName;
+	}
+
+	@Deprecated
+	public boolean isFlag() {
+		return this.flag;
+	}
+
+	public Comparator<?> getComparator() {
+		return this.comparator;
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/specific/InvalidDefaultValueCharacterProperties.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2012-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationsample.specific;
+
+import org.springframework.boot.configurationsample.ConfigurationProperties;
+import org.springframework.boot.configurationsample.DefaultValue;
+
+/**
+ * Demonstrates that an invalid default character value leads to a compilation failure.
+ *
+ * @author Stephane Nicoll
+ */
+@ConfigurationProperties("test")
+public class InvalidDefaultValueCharacterProperties {
+
+	private final char letter;
+
+	public InvalidDefaultValueCharacterProperties(@DefaultValue("bad") char letter) {
+		this.letter = letter;
+	}
+
+	public char getLetter() {
+		return this.letter;
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/specific/InvalidDefaultValueFloatingPointProperties.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2012-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationsample.specific;
+
+import org.springframework.boot.configurationsample.ConfigurationProperties;
+import org.springframework.boot.configurationsample.DefaultValue;
+
+/**
+ * Demonstrates that an invalid default floating point value leads to a compilation
+ * failure.
+ *
+ * @author Stephane Nicoll
+ */
+@ConfigurationProperties("test")
+public class InvalidDefaultValueFloatingPointProperties {
+
+	private final Double ratio;
+
+	public InvalidDefaultValueFloatingPointProperties(
+			@DefaultValue("55.55.33") Double ratio) {
+		this.ratio = ratio;
+	}
+
+	public Double getRatio() {
+		return this.ratio;
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/specific/InvalidDefaultValueNumberProperties.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2012-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationsample.specific;
+
+import org.springframework.boot.configurationsample.ConfigurationProperties;
+import org.springframework.boot.configurationsample.DefaultValue;
+
+/**
+ * Demonstrates that an invalid default number value leads to a compilation failure.
+ *
+ * @author Stephane Nicoll
+ */
+@ConfigurationProperties("test")
+public class InvalidDefaultValueNumberProperties {
+
+	private final int counter;
+
+	public InvalidDefaultValueNumberProperties(@DefaultValue("invalid") int counter) {
+		this.counter = counter;
+	}
+
+	public int getCounter() {
+		return this.counter;
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/specific/TwoConstructorsExample.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2012-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationsample.specific;
+
+/**
+ * A type with more than one constructor.
+ *
+ * @author Stephane Nicoll
+ */
+public class TwoConstructorsExample {
+
+	private String name;
+
+	public TwoConstructorsExample() {
+	}
+
+	public TwoConstructorsExample(String name) {
+		this.name = name;
+	}
+
+	public String getName() {
+		return this.name;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+
+}

src/checkstyle/checkstyle-suppressions.xml

@@ -13,6 +13,7 @@
 	<suppress files="[\\/]src[\\/]main[\\/]java[\\/]sample[\\/]" checks="ImportControl" />
 	<suppress files="[\\/]src[\\/]test[\\/]java[\\/]sample[\\/]" checks="ImportControl" />
 	<suppress files="[\\/]src[\\/]test[\\/]java[\\/]" checks="Javadoc*" />
+	<suppress files="[\\/]src[\\/]test[\\/]java[\\/]" checks="NonEmptyAtclauseDescription" />
 	<suppress files="[\\/]autoconfigure[\\/]" checks="JavadocType" />
 	<suppress files="[\\/]autoconfigure[\\/]" checks="JavadocVariable" />
 	<suppress files="[\\/]spring-boot-docs[\\/]" checks="JavadocType" />