Improve null-safety of core/spring-boot

See gh-46926

core/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesScanRegistrar.java

@@ -20,6 +20,8 @@ import java.util.Arrays;
 import java.util.LinkedHashSet;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
@@ -50,9 +52,9 @@ class ConfigurationPropertiesScanRegistrar implements ImportBeanDefinitionRegist
 
 	private final Environment environment;
 
-	private final ResourceLoader resourceLoader;
+	private final @Nullable ResourceLoader resourceLoader;
 
-	ConfigurationPropertiesScanRegistrar(Environment environment, ResourceLoader resourceLoader) {
+	ConfigurationPropertiesScanRegistrar(Environment environment, @Nullable ResourceLoader resourceLoader) {
 		this.environment = environment;
 		this.resourceLoader = resourceLoader;
 	}

core/spring-boot/src/main/java/org/springframework/boot/context/properties/source/CachingConfigurationPropertySource.java

@@ -38,7 +38,7 @@ interface CachingConfigurationPropertySource {
 	 * @return a {@link ConfigurationPropertyCaching} instance or {@code null} if the
 	 * source does not support caching.
 	 */
-	static @Nullable ConfigurationPropertyCaching find(ConfigurationPropertySource source) {
+	static @Nullable ConfigurationPropertyCaching find(@Nullable ConfigurationPropertySource source) {
 		if (source instanceof CachingConfigurationPropertySource cachingSource) {
 			return cachingSource.getCaching();
 		}

core/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationProperty.java

@@ -22,6 +22,7 @@ import org.springframework.boot.origin.Origin;
 import org.springframework.boot.origin.OriginProvider;
 import org.springframework.boot.origin.OriginTrackedValue;
 import org.springframework.core.style.ToStringCreator;
+import org.springframework.lang.Contract;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 
@@ -124,6 +125,7 @@ public final class ConfigurationProperty implements OriginProvider, Comparable<C
 		return this.name.compareTo(other.name);
 	}
 
+	@Contract("_, !null -> !null")
 	static @Nullable ConfigurationProperty of(ConfigurationPropertyName name, @Nullable OriginTrackedValue value) {
 		if (value == null) {
 			return null;
@@ -131,6 +133,7 @@ public final class ConfigurationProperty implements OriginProvider, Comparable<C
 		return new ConfigurationProperty(name, value.getValue(), value.getOrigin());
 	}
 
+	@Contract("_, _, !null, _ -> !null")
 	static @Nullable ConfigurationProperty of(@Nullable ConfigurationPropertySource source,
 			ConfigurationPropertyName name, @Nullable Object value, @Nullable Origin origin) {
 		if (value == null) {

core/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertyName.java

@@ -210,7 +210,7 @@ public final class ConfigurationPropertyName implements Comparable<Configuration
 	 * @return a new {@link ConfigurationPropertyName}
 	 * @throws InvalidConfigurationPropertyNameException if the result is not valid
 	 */
-	public ConfigurationPropertyName append(String suffix) {
+	public ConfigurationPropertyName append(@Nullable String suffix) {
 		if (!StringUtils.hasLength(suffix)) {
 			return this;
 		}
@@ -625,7 +625,7 @@ public final class ConfigurationPropertyName implements Comparable<Configuration
 	 * @param name the name to test
 	 * @return {@code true} if the name is valid
 	 */
-	public static boolean isValid(CharSequence name) {
+	public static boolean isValid(@Nullable CharSequence name) {
 		return of(name, true) != null;
 	}
 
@@ -636,7 +636,7 @@ public final class ConfigurationPropertyName implements Comparable<Configuration
 	 * @throws InvalidConfigurationPropertyNameException if the name is not valid
 	 */
 	@SuppressWarnings("NullAway") // See https://github.com/uber/NullAway/issues/1232
-	public static ConfigurationPropertyName of(CharSequence name) {
+	public static ConfigurationPropertyName of(@Nullable CharSequence name) {
 		return of(name, false);
 	}
 
@@ -647,7 +647,7 @@ public final class ConfigurationPropertyName implements Comparable<Configuration
 	 * @return a {@link ConfigurationPropertyName} instance
 	 * @since 2.3.1
 	 */
-	public static @Nullable ConfigurationPropertyName ofIfValid(CharSequence name) {
+	public static @Nullable ConfigurationPropertyName ofIfValid(@Nullable CharSequence name) {
 		return of(name, true);
 	}
 
@@ -660,7 +660,7 @@ public final class ConfigurationPropertyName implements Comparable<Configuration
 	 * {@code returnNullIfInvalid} is {@code false}
 	 */
 	@Contract("_, false -> !null")
-	static @Nullable ConfigurationPropertyName of(CharSequence name, boolean returnNullIfInvalid) {
+	static @Nullable ConfigurationPropertyName of(@Nullable CharSequence name, boolean returnNullIfInvalid) {
 		Elements elements = elementsOf(name, returnNullIfInvalid, ElementsParser.DEFAULT_CAPACITY);
 		return (elements != null) ? new ConfigurationPropertyName(elements) : null;
 	}

core/spring-boot/src/main/java/org/springframework/boot/diagnostics/AbstractFailureAnalyzer.java

@@ -61,7 +61,7 @@ public abstract class AbstractFailureAnalyzer<T extends Throwable> implements Fa
 	}
 
 	@SuppressWarnings("unchecked")
-	protected final <E extends Throwable> @Nullable E findCause(Throwable failure, Class<E> type) {
+	protected final <E extends Throwable> @Nullable E findCause(@Nullable Throwable failure, Class<E> type) {
 		while (failure != null) {
 			if (type.isInstance(failure)) {
 				return (E) failure;

core/spring-boot/src/main/java/org/springframework/boot/diagnostics/analyzer/MutuallyExclusiveConfigurationPropertiesFailureAnalyzer.java

@@ -48,9 +48,9 @@ import org.springframework.core.env.PropertySource;
 class MutuallyExclusiveConfigurationPropertiesFailureAnalyzer
 		extends AbstractFailureAnalyzer<MutuallyExclusiveConfigurationPropertiesException> {
 
-	private final ConfigurableEnvironment environment;
+	private final @Nullable ConfigurableEnvironment environment;
 
-	MutuallyExclusiveConfigurationPropertiesFailureAnalyzer(Environment environment) {
+	MutuallyExclusiveConfigurationPropertiesFailureAnalyzer(@Nullable Environment environment) {
 		this.environment = (ConfigurableEnvironment) environment;
 	}
 

core/spring-boot/src/main/java/org/springframework/boot/json/AbstractJsonParser.java

@@ -34,11 +34,11 @@ import org.springframework.util.ReflectionUtils;
  */
 public abstract class AbstractJsonParser implements JsonParser {
 
-	protected final Map<String, Object> parseMap(String json, Function<String, Map<String, Object>> parser) {
+	protected final Map<String, Object> parseMap(@Nullable String json, Function<String, Map<String, Object>> parser) {
 		return trimParse(json, "{", parser);
 	}
 
-	protected final List<Object> parseList(String json, Function<String, List<Object>> parser) {
+	protected final List<Object> parseList(@Nullable String json, Function<String, List<Object>> parser) {
 		return trimParse(json, "[", parser);
 	}
 

core/spring-boot/src/main/java/org/springframework/boot/json/BasicJsonParser.java

@@ -44,12 +44,12 @@ public class BasicJsonParser extends AbstractJsonParser {
 	private static final int MAX_DEPTH = 1000;
 
 	@Override
-	public Map<String, Object> parseMap(String json) {
+	public Map<String, Object> parseMap(@Nullable String json) {
 		return tryParse(() -> parseMap(json, (jsonToParse) -> parseMapInternal(0, jsonToParse)), Exception.class);
 	}
 
 	@Override
-	public List<Object> parseList(String json) {
+	public List<Object> parseList(@Nullable String json) {
 		return tryParse(() -> parseList(json, (jsonToParse) -> parseListInternal(0, jsonToParse)), Exception.class);
 	}
 

core/spring-boot/src/main/java/org/springframework/boot/json/GsonJsonParser.java

@@ -22,6 +22,7 @@ import java.util.Map;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.reflect.TypeToken;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Thin wrapper to adapt {@link Gson} to a {@link JsonParser}.
@@ -40,13 +41,13 @@ public class GsonJsonParser extends AbstractJsonParser {
 	private final Gson gson = new GsonBuilder().create();
 
 	@Override
-	public Map<String, Object> parseMap(String json) {
+	public Map<String, Object> parseMap(@Nullable String json) {
 		return tryParse(() -> parseMap(json, (trimmed) -> this.gson.fromJson(trimmed, MAP_TYPE.getType())),
 				Exception.class);
 	}
 
 	@Override
-	public List<Object> parseList(String json) {
+	public List<Object> parseList(@Nullable String json) {
 		return tryParse(() -> parseList(json, (trimmed) -> this.gson.fromJson(trimmed, LIST_TYPE.getType())),
 				Exception.class);
 	}

core/spring-boot/src/main/java/org/springframework/boot/json/JacksonJsonParser.java

@@ -53,12 +53,12 @@ public class JacksonJsonParser extends AbstractJsonParser {
 	}
 
 	@Override
-	public Map<String, Object> parseMap(String json) {
+	public Map<String, Object> parseMap(@Nullable String json) {
 		return tryParse(() -> getObjectMapper().readValue(json, MAP_TYPE), Exception.class);
 	}
 
 	@Override
-	public List<Object> parseList(String json) {
+	public List<Object> parseList(@Nullable String json) {
 		return tryParse(() -> getObjectMapper().readValue(json, LIST_TYPE), Exception.class);
 	}
 

core/spring-boot/src/main/java/org/springframework/boot/json/JsonParser.java

@@ -19,6 +19,8 @@ package org.springframework.boot.json;
 import java.util.List;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Parser that can read JSON formatted strings into {@link Map}s or {@link List}s.
  *
@@ -37,7 +39,7 @@ public interface JsonParser {
 	 * @return the parsed JSON as a map
 	 * @throws JsonParseException if the JSON cannot be parsed
 	 */
-	Map<String, Object> parseMap(String json) throws JsonParseException;
+	Map<String, Object> parseMap(@Nullable String json) throws JsonParseException;
 
 	/**
 	 * Parse the specified JSON string into a List.
@@ -45,6 +47,6 @@ public interface JsonParser {
 	 * @return the parsed JSON as a list
 	 * @throws JsonParseException if the JSON cannot be parsed
 	 */
-	List<Object> parseList(String json) throws JsonParseException;
+	List<Object> parseList(@Nullable String json) throws JsonParseException;
 
 }

core/spring-boot/src/main/java/org/springframework/boot/logging/DelegatingLoggingSystemFactory.java

@@ -28,13 +28,13 @@ import org.jspecify.annotations.Nullable;
  */
 class DelegatingLoggingSystemFactory implements LoggingSystemFactory {
 
-	private final @Nullable Function<ClassLoader, List<LoggingSystemFactory>> delegates;
+	private final @Nullable Function<ClassLoader, @Nullable List<LoggingSystemFactory>> delegates;
 
 	/**
 	 * Create a new {@link DelegatingLoggingSystemFactory} instance.
 	 * @param delegates a function that provides the delegates
 	 */
-	DelegatingLoggingSystemFactory(@Nullable Function<ClassLoader, List<LoggingSystemFactory>> delegates) {
+	DelegatingLoggingSystemFactory(@Nullable Function<ClassLoader, @Nullable List<LoggingSystemFactory>> delegates) {
 		this.delegates = delegates;
 	}
 

core/spring-boot/src/main/java/org/springframework/boot/logging/log4j2/ColorConverter.java

@@ -120,7 +120,7 @@ public final class ColorConverter extends LogEventPatternConverter {
 	 * @param options the options
 	 * @return a new instance, or {@code null} if the options are invalid
 	 */
-	public static @Nullable ColorConverter newInstance(Configuration config, @Nullable String[] options) {
+	public static @Nullable ColorConverter newInstance(@Nullable Configuration config, @Nullable String[] options) {
 		if (options.length < 1) {
 			LOGGER.error("Incorrect number of options on style. Expected at least 1, received {}", options.length);
 			return null;

core/spring-boot/src/main/java/org/springframework/boot/logging/log4j2/EnclosedInSquareBracketsConverter.java

@@ -67,7 +67,8 @@ public final class EnclosedInSquareBracketsConverter extends LogEventPatternConv
 	 * @param options the options
 	 * @return a new instance, or {@code null} if the options are invalid
 	 */
-	public static @Nullable EnclosedInSquareBracketsConverter newInstance(Configuration config, String[] options) {
+	public static @Nullable EnclosedInSquareBracketsConverter newInstance(@Nullable Configuration config,
+			String[] options) {
 		if (options.length < 1) {
 			LOGGER.error("Incorrect number of options on style. Expected at least 1, received {}", options.length);
 			return null;

core/spring-boot/src/main/java/org/springframework/boot/logging/logback/EnclosedInSquareBracketsConverter.java

@@ -32,7 +32,7 @@ import org.springframework.util.StringUtils;
 public class EnclosedInSquareBracketsConverter extends CompositeConverter<ILoggingEvent> {
 
 	@Override
-	protected String transform(ILoggingEvent event, String in) {
+	protected String transform(ILoggingEvent event, @Nullable String in) {
 		in = (!StringUtils.hasLength(in)) ? resolveFromFirstOption(event) : in;
 		return (!StringUtils.hasLength(in)) ? "" : "[%s] ".formatted(in);
 	}

core/spring-boot/src/main/java/org/springframework/boot/logging/logback/LogbackLoggingSystemProperties.java

@@ -68,7 +68,7 @@ public class LogbackLoggingSystemProperties extends LoggingSystemProperties {
 	 * @since 3.2.0
 	 */
 	public LogbackLoggingSystemProperties(Environment environment,
-			Function<@Nullable String, @Nullable String> defaultValueResolver,
+			@Nullable Function<@Nullable String, @Nullable String> defaultValueResolver,
 			@Nullable BiConsumer<String, @Nullable String> setter) {
 		super(environment, defaultValueResolver, setter);
 	}

core/spring-boot/src/main/java/org/springframework/boot/logging/structured/StructuredLoggingJsonProperties.java

@@ -56,11 +56,11 @@ import org.springframework.util.Assert;
  * @author Yanming Zhou
  */
 record StructuredLoggingJsonProperties(Set<String> include, Set<String> exclude, Map<String, String> rename,
-		Map<String, String> add, StackTrace stackTrace, Context context,
+		Map<String, String> add, @Nullable StackTrace stackTrace, @Nullable Context context,
 		Set<Class<? extends StructuredLoggingJsonMembersCustomizer<?>>> customizer) {
 
 	StructuredLoggingJsonProperties(Set<String> include, Set<String> exclude, Map<String, String> rename,
-			Map<String, String> add, StackTrace stackTrace, Context context,
+			Map<String, String> add, @Nullable StackTrace stackTrace, @Nullable Context context,
 			@Nullable Set<Class<? extends StructuredLoggingJsonMembersCustomizer<?>>> customizer) {
 		this.include = include;
 		this.exclude = exclude;
@@ -98,8 +98,9 @@ record StructuredLoggingJsonProperties(Set<String> include, Set<String> exclude,
 	 * @param includeCommonFrames whether common frames should be included
 	 * @param includeHashes whether stack trace hashes should be included
 	 */
-	record StackTrace(@Nullable String printer, Root root, Integer maxLength, Integer maxThrowableDepth,
-			Boolean includeCommonFrames, Boolean includeHashes) {
+	record StackTrace(@Nullable String printer, @Nullable Root root, @Nullable Integer maxLength,
+			@Nullable Integer maxThrowableDepth, @Nullable Boolean includeCommonFrames,
+			@Nullable Boolean includeHashes) {
 
 		@Nullable StackTracePrinter createPrinter() {
 			String name = sanitizePrinter();

core/spring-boot/src/main/java/org/springframework/boot/origin/OriginLookup.java

@@ -47,7 +47,7 @@ public interface OriginLookup<K> {
 	 * @return an {@link Origin} or {@code null}
 	 */
 	@SuppressWarnings("unchecked")
-	static <K> @Nullable Origin getOrigin(Object source, K key) {
+	static <K> @Nullable Origin getOrigin(@Nullable Object source, K key) {
 		if (!(source instanceof OriginLookup)) {
 			return null;
 		}

core/spring-boot/src/main/java/org/springframework/boot/ssl/jks/JksSslStoreDetails.java

@@ -61,7 +61,7 @@ public record JksSslStoreDetails(@Nullable String type, @Nullable String provide
 	 * @param location the location
 	 * @return a new {@link JksSslStoreDetails} instance.
 	 */
-	public static JksSslStoreDetails forLocation(String location) {
+	public static JksSslStoreDetails forLocation(@Nullable String location) {
 		return new JksSslStoreDetails(null, null, location, null);
 	}
 

core/spring-boot/src/main/java/org/springframework/boot/ssl/pem/PemSslStore.java

@@ -78,7 +78,9 @@ public interface PemSslStore {
 	 * @return a new {@link PemSslStore} instance
 	 */
 	default PemSslStore withAlias(@Nullable String alias) {
-		return of(type(), alias, password(), certificates(), privateKey());
+		List<X509Certificate> certificates = certificates();
+		Assert.notNull(certificates, "'certificates' must not be null");
+		return of(type(), alias, password(), certificates, privateKey());
 	}
 
 	/**
@@ -87,7 +89,9 @@ public interface PemSslStore {
 	 * @return a new {@link PemSslStore} instance
 	 */
 	default PemSslStore withPassword(@Nullable String password) {
-		return of(type(), alias(), password, certificates(), privateKey());
+		List<X509Certificate> certificates = certificates();
+		Assert.notNull(certificates, "'certificates' must not be null");
+		return of(type(), alias(), password, certificates, privateKey());
 	}
 
 	/**
@@ -123,7 +127,7 @@ public interface PemSslStore {
 	 * @param privateKey the private key
 	 * @return a new {@link PemSslStore} instance
 	 */
-	static PemSslStore of(String type, List<X509Certificate> certificates, PrivateKey privateKey) {
+	static PemSslStore of(@Nullable String type, List<X509Certificate> certificates, @Nullable PrivateKey privateKey) {
 		return of(type, null, null, certificates, privateKey);
 	}
 
@@ -134,7 +138,7 @@ public interface PemSslStore {
 	 * @param privateKey the private key
 	 * @return a new {@link PemSslStore} instance
 	 */
-	static PemSslStore of(List<X509Certificate> certificates, PrivateKey privateKey) {
+	static PemSslStore of(List<X509Certificate> certificates, @Nullable PrivateKey privateKey) {
 		return of(null, null, null, certificates, privateKey);
 	}
 
@@ -151,7 +155,7 @@ public interface PemSslStore {
 	 * @return a new {@link PemSslStore} instance
 	 */
 	static PemSslStore of(@Nullable String type, @Nullable String alias, @Nullable String password,
-			@Nullable List<X509Certificate> certificates, @Nullable PrivateKey privateKey) {
+			List<X509Certificate> certificates, @Nullable PrivateKey privateKey) {
 		Assert.notEmpty(certificates, "'certificates' must not be empty");
 		return new PemSslStore() {
 

core/spring-boot/src/main/java/org/springframework/boot/ssl/pem/PemSslStoreDetails.java

@@ -151,7 +151,7 @@ public record PemSslStoreDetails(@Nullable String type, @Nullable String alias,
 	 * reference to the resource to load)
 	 * @return a new {@link PemSslStoreDetails} instance.
 	 */
-	public static PemSslStoreDetails forCertificate(String certificate) {
+	public static PemSslStoreDetails forCertificate(@Nullable String certificate) {
 		return forCertificates(certificate);
 	}
 
@@ -163,7 +163,7 @@ public record PemSslStoreDetails(@Nullable String type, @Nullable String alias,
 	 * @return a new {@link PemSslStoreDetails} instance.
 	 * @since 3.2.0
 	 */
-	public static PemSslStoreDetails forCertificates(String certificates) {
+	public static PemSslStoreDetails forCertificates(@Nullable String certificates) {
 		return new PemSslStoreDetails(null, certificates, null);
 	}
 

core/spring-boot/src/main/java/org/springframework/boot/system/ApplicationPid.java

@@ -46,7 +46,7 @@ public class ApplicationPid {
 		this.pid = currentProcessPid();
 	}
 
-	protected ApplicationPid(Long pid) {
+	protected ApplicationPid(@Nullable Long pid) {
 		this.pid = pid;
 	}
 

core/spring-boot/src/main/java/org/springframework/boot/web/servlet/support/SpringBootServletInitializer.java

@@ -151,7 +151,7 @@ public abstract class SpringBootServletInitializer implements WebApplicationInit
 		}
 	}
 
-	protected WebApplicationContext createRootApplicationContext(ServletContext servletContext) {
+	protected @Nullable WebApplicationContext createRootApplicationContext(ServletContext servletContext) {
 		SpringApplicationBuilder builder = createSpringApplicationBuilder();
 		builder.main(getClass());
 		ApplicationContext parent = getExistingRootWebApplicationContext(servletContext);
@@ -201,7 +201,7 @@ public abstract class SpringBootServletInitializer implements WebApplicationInit
 	 * @param application the application to run
 	 * @return the {@link WebApplicationContext}
 	 */
-	protected WebApplicationContext run(SpringApplication application) {
+	protected @Nullable WebApplicationContext run(SpringApplication application) {
 		return (WebApplicationContext) application.run();
 	}