Add @Contract and @CheckReturnValue annotations.

Closes: #3195
Original pull request: #3210

Author: mp911de

src/main/java/org/springframework/data/annotation/AccessType.java

@@ -34,8 +34,6 @@
 
 	/**
 	 * The access type to be used.
-	 *
-	 * @return
 	 */
 	Type value();
 

src/main/java/org/springframework/data/annotation/PersistenceCreator.java

@@ -29,4 +29,5 @@
  */
 @Retention(RetentionPolicy.RUNTIME)
 @Target({ ElementType.CONSTRUCTOR, ElementType.METHOD, ElementType.ANNOTATION_TYPE })
-public @interface PersistenceCreator {}
+public @interface PersistenceCreator {
+}

src/main/java/org/springframework/data/annotation/Reference.java

@@ -36,17 +36,13 @@
 	/**
 	 * Explicitly define the target type of the reference. Used in case the annotated property is not the target type but
 	 * rather an identifier and/or if that identifier type is not uniquely identifying the target entity.
-	 *
-	 * @return
 	 */
 	@AliasFor(attribute = "to")
 	Class<?> value() default Class.class;
 
 	/**
 	 * Explicitly define the target type of the reference. Used in case the annotated property is not the target type but
 	 * rather an identifier and/or if that identifier type is not uniquely identifying the target entity.
-	 *
-	 * @return
 	 */
 	@AliasFor(attribute = "value")
 	Class<?> to() default Class.class;

src/main/java/org/springframework/data/annotation/TypeAlias.java

@@ -29,6 +29,7 @@
  * {@link PersistentEntity}s.
  *
  * @author Oliver Gierke
+ * @see org.springframework.data.mapping.Alias
  */
 @Documented
 @Inherited
@@ -38,9 +39,7 @@
 public @interface TypeAlias {
 
 	/**
-	 * The type alias to be used when persisting
-	 *
-	 * @return
+	 * The type alias to be used when persisting.
 	 */
 	String value();
 }

src/main/java/org/springframework/data/annotation/Version.java

@@ -33,5 +33,4 @@
 @Retention(RUNTIME)
 @Target(value = { FIELD, METHOD, ANNOTATION_TYPE })
 public @interface Version {
-
 }

src/main/java/org/springframework/data/aot/AotContext.java

@@ -140,7 +140,7 @@ default Set<Class<?>> scanPackageForTypes(Collection<Class<? extends Annotation>
 	}
 
 	/**
-	 * Returns a {@link IntrospectedBeanDefinition} to obtain further detail about the underlying bean definition. A
+	 * Returns a {@link IntrospectedBeanDefinition} to obtain further detail about the underlying bean definition. An
 	 * introspected bean definition can also point to an absent bean definition.
 	 *
 	 * @param reference {@link BeanReference} to the managed bean.
@@ -151,7 +151,7 @@ default IntrospectedBeanDefinition introspectBeanDefinition(BeanReference refere
 	}
 
 	/**
-	 * Returns a {@link IntrospectedBeanDefinition} to obtain further detail about the underlying bean definition. A
+	 * Returns a {@link IntrospectedBeanDefinition} to obtain further detail about the underlying bean definition. An
 	 * introspected bean definition can also point to an absent bean definition.
 	 *
 	 * @param beanName {@link String} containing the {@literal name} of the bean to evaluate; must not be {@literal null}.
@@ -251,7 +251,6 @@ interface IntrospectedBeanDefinition {
 		 *           bean}.
 		 * @see BeanDefinition
 		 */
-
 		BeanDefinition getBeanDefinition() throws NoSuchBeanDefinitionException;
 
 		/**

src/main/java/org/springframework/data/aot/AuditingBeanRegistrationAotProcessor.java

@@ -39,7 +39,6 @@
  */
 class AuditingBeanRegistrationAotProcessor implements BeanRegistrationAotProcessor {
 
-
 	@Nullable
 	@Override
 	public BeanRegistrationAotContribution processAheadOfTime(RegisteredBean registeredBean) {

src/main/java/org/springframework/data/aot/ManagedTypesBeanFactoryInitializationAotProcessor.java

@@ -29,6 +29,7 @@
 import org.springframework.beans.factory.support.BeanDefinitionBuilder;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.data.domain.ManagedTypes;
+import org.springframework.lang.Contract;
 import org.springframework.lang.Nullable;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.ObjectUtils;
@@ -44,10 +45,11 @@
  */
 public class ManagedTypesBeanFactoryInitializationAotProcessor implements BeanFactoryInitializationAotProcessor {
 
-	private static final Log logger = LogFactory.getLog(BeanFactoryInitializationAotProcessor.class);
+	private static final Log logger = LogFactory.getLog(ManagedTypesBeanFactoryInitializationAotProcessor.class);
 
-	@Nullable
 	@Override
+	@Nullable
+	@Contract("_ -> null")
 	public BeanFactoryInitializationAotContribution processAheadOfTime(ConfigurableListableBeanFactory beanFactory) {
 
 		processManagedTypes(beanFactory);
@@ -71,9 +73,9 @@ private void postProcessManagedTypes(ConfigurableListableBeanFactory beanFactory
 
 		if (hasConstructorArguments(beanDefinition)) {
 
-			ValueHolder argumentValue = beanDefinition.getConstructorArgumentValues().getArgumentValue(0, null, null, null);
+			ValueHolder holder = beanDefinition.getConstructorArgumentValues().getArgumentValue(0, null, null, null);
 
-			if (argumentValue.getValue()instanceof Supplier supplier) {
+			if (holder != null && holder.getValue() instanceof Supplier<?> supplier) {
 
 				if (logger.isDebugEnabled()) {
 					logger.info(String.format("Replacing ManagedType bean definition %s.", beanName));

src/main/java/org/springframework/data/aot/ManagedTypesBeanRegistrationAotProcessor.java

@@ -78,9 +78,9 @@ private ManagedTypes resolveManagedTypes(RegisteredBean registeredBean) {
 		if (beanDefinition.hasConstructorArgumentValues()) {
 
 			ValueHolder indexedArgumentValue = beanDefinition.getConstructorArgumentValues().getIndexedArgumentValue(0, null);
-			Object value = indexedArgumentValue.getValue();
 
-			if (value instanceof Collection<?> values && values.stream().allMatch(it -> it instanceof Class)) {
+			if (indexedArgumentValue != null && indexedArgumentValue.getValue() instanceof Collection<?> values
+					&& values.stream().allMatch(it -> it instanceof Class)) {
 				return ManagedTypes.fromIterable((Collection<Class<?>>) values);
 			}
 		}
@@ -115,7 +115,6 @@ private ManagedTypes resolveManagedTypes(RegisteredBean registeredBean) {
 	 * @param managedTypes never {@literal null}.
 	 * @return new instance of {@link BeanRegistrationAotContribution} or {@literal null} if nothing to do.
 	 */
-	@Nullable
 	protected BeanRegistrationAotContribution contribute(AotContext aotContext, ManagedTypes managedTypes,
 			RegisteredBean registeredBean) {
 		return new ManagedTypesRegistrationAotContribution(managedTypes, registeredBean, this::contributeType);

src/main/java/org/springframework/data/aot/ManagedTypesRegistrationAotContribution.java

@@ -15,7 +15,6 @@
  */
 package org.springframework.data.aot;
 
-import java.lang.reflect.Executable;
 import java.lang.reflect.Method;
 import java.util.Collections;
 import java.util.List;
@@ -69,8 +68,8 @@
  * @author John Blum
  * @author Christoph Strobl
  * @author Mark Paluch
- * @see org.springframework.beans.factory.aot.BeanRegistrationAotContribution
  * @since 3.0
+ * @see org.springframework.beans.factory.aot.BeanRegistrationAotContribution
  */
 class ManagedTypesRegistrationAotContribution implements RegisteredBeanAotContribution {
 
@@ -126,7 +125,7 @@ static class ManagedTypesInstanceCodeFragment extends BeanRegistrationCodeFragme
 		public static final ResolvableType MANAGED_TYPES_TYPE = ResolvableType.forType(ManagedTypes.class);
 		private final List<Class<?>> sourceTypes;
 		private final RegisteredBean source;
-		private final Lazy<Method> instanceMethod = Lazy.of(this::findInstanceFactory);
+		private final Lazy<Method> instanceMethod;
 
 		private static final TypeName WILDCARD = WildcardTypeName.subtypeOf(Object.class);
 		private static final TypeName CLASS_OF_ANY = ParameterizedTypeName.get(ClassName.get(Class.class), WILDCARD);
@@ -139,6 +138,7 @@ protected ManagedTypesInstanceCodeFragment(List<Class<?>> sourceTypes, Registere
 
 			this.sourceTypes = sourceTypes;
 			this.source = source;
+			this.instanceMethod = Lazy.of(() -> findInstanceFactory(source.getBeanClass()));
 		}
 
 		@Override
@@ -230,15 +230,15 @@ private CodeBlock toCodeBlock(List<Class<?>> values, boolean allPublic) {
 		}
 
 		@Nullable
-		private Method findInstanceFactory() {
+		private static Method findInstanceFactory(Class<?> beanClass) {
 
-			for (Method beanMethod : ReflectionUtils.getDeclaredMethods(source.getBeanClass())) {
+			for (Method beanMethod : ReflectionUtils.getDeclaredMethods(beanClass)) {
 
 				if (!isInstanceFactory(beanMethod)) {
 					continue;
 				}
 
-				ResolvableType parameterType = ResolvableType.forMethodParameter(beanMethod, 0, source.getBeanClass());
+				ResolvableType parameterType = ResolvableType.forMethodParameter(beanMethod, 0, beanClass);
 
 				if (parameterType.isAssignableFrom(LIST_TYPE) || parameterType.isAssignableFrom(MANAGED_TYPES_TYPE)) {
 					return beanMethod;

src/main/java/org/springframework/data/aot/PublicMethodReflectiveProcessor.java

@@ -20,6 +20,8 @@
 import org.springframework.aot.hint.annotation.SimpleReflectiveProcessor;
 
 /**
+ * Extension to {@link SimpleReflectiveProcessor} to register reflective hints for invoking public methods.
+ *
  * @author Christoph Strobl
  */
 public class PublicMethodReflectiveProcessor extends SimpleReflectiveProcessor {

src/main/java/org/springframework/data/aot/RegisteredBeanAotContribution.java

@@ -19,7 +19,7 @@
 import org.springframework.beans.factory.support.RegisteredBean;
 
 /**
- * Extension to {@link BeanRegistrationAotContribution} that bases its contribution on a {@link RegisteredBean}. This
+ * Extension to {@link BeanRegistrationAotContribution} that bases its contribution to a {@link RegisteredBean}. This
  * interface exposes its {@link #getSource() source}.
  *
  * @author Christoph Strobl

src/main/java/org/springframework/data/auditing/AuditableBeanWrapper.java

@@ -18,6 +18,9 @@
 import java.time.temporal.TemporalAccessor;
 import java.util.Optional;
 
+import org.springframework.lang.Contract;
+import org.springframework.lang.Nullable;
+
 /**
  * Interface to abstract the ways setting the auditing information can be implemented.
  *
@@ -31,7 +34,9 @@ public interface AuditableBeanWrapper<T> {
 	 *
 	 * @param value
 	 */
-	Object setCreatedBy(Object value);
+	@Nullable
+	@Contract("null -> null; !null -> !null")
+	Object setCreatedBy(@Nullable Object value);
 
 	/**
 	 * Set the date the object was created.
@@ -45,7 +50,9 @@ public interface AuditableBeanWrapper<T> {
 	 *
 	 * @param value
 	 */
-	Object setLastModifiedBy(Object value);
+	@Nullable
+	@Contract("null -> null; !null -> !null")
+	Object setLastModifiedBy(@Nullable Object value);
 
 	/**
 	 * Returns the date of the last modification date of the backing bean.

src/main/java/org/springframework/data/auditing/AuditingHandler.java

@@ -104,9 +104,10 @@ Auditor<?> getAuditor() {
 				.orElse(Auditor.none());
 	}
 
+	@Override
 	public void afterPropertiesSet() {
 
-		if (!auditorAware.isPresent()) {
+		if (auditorAware.isEmpty()) {
 			logger.debug("No AuditorAware set; Auditing will not be applied");
 		}
 	}

src/main/java/org/springframework/data/auditing/AuditingHandlerSupport.java

@@ -151,11 +151,6 @@ private <T> T touch(Auditor<?> auditor, T target, boolean isNew) {
 
 	/**
 	 * Sets modifying and creating auditor. Creating auditor is only set on new auditables.
-	 *
-	 * @param auditor
-	 * @param wrapper
-	 * @param isNew
-	 * @return
 	 */
 	private void touchAuditor(Auditor<?> auditor, AuditableBeanWrapper<?> wrapper, boolean isNew) {
 
@@ -176,10 +171,6 @@ private void touchAuditor(Auditor<?> auditor, AuditableBeanWrapper<?> wrapper, b
 
 	/**
 	 * Touches the auditable regarding modification and creation date. Creation date is only set on new auditables.
-	 *
-	 * @param wrapper
-	 * @param isNew
-	 * @return
 	 */
 	private Optional<TemporalAccessor> touchDate(AuditableBeanWrapper<?> wrapper, boolean isNew) {
 

src/main/java/org/springframework/data/auditing/Auditor.java

@@ -28,7 +28,7 @@
  */
 class Auditor<T> {
 
-	private static final Auditor NONE = new Auditor(null) {
+	private static final Auditor<Object> NONE = new Auditor<>(null) {
 
 		@Override
 		public boolean isPresent() {
@@ -59,6 +59,7 @@ public T getValue() {
 	 * @param <T>
 	 * @return {@link Auditor#none()} if the given {@literal source} is {@literal null}. }
 	 */
+	@SuppressWarnings({ "unchecked", "rawtypes" })
 	public static <T> Auditor<T> of(@Nullable T source) {
 
 		if (source instanceof Auditor) {
@@ -77,7 +78,7 @@ public static <T> Auditor<T> of(@Nullable T source) {
 	 * @param <T>
 	 * @return {@link Auditor#none()} if the given {@literal source} is {@literal null}. }
 	 */
-	public static <T> Auditor<T> ofOptional(@Nullable Optional<T> source) {
+	public static <T> Auditor<T> ofOptional(Optional<T> source) {
 		return Auditor.of(source.orElse(null));
 	}
 
@@ -87,8 +88,9 @@ public static <T> Auditor<T> ofOptional(@Nullable Optional<T> source) {
 	 * @param <T>
 	 * @return never {@literal null}.
 	 */
+	@SuppressWarnings("unchecked")
 	public static <T> Auditor<T> none() {
-		return NONE;
+		return (Auditor<T>) NONE;
 	}
 
 	/**

src/main/java/org/springframework/data/auditing/DefaultAuditableBeanWrapperFactory.java

@@ -115,7 +115,7 @@ public AuditableInterfaceBeanWrapper(ConversionService conversionService,
 		}
 
 		@Override
-		public Object setCreatedBy(Object value) {
+		public Object setCreatedBy(@Nullable Object value) {
 
 			auditable.setCreatedBy(value);
 			return value;
@@ -267,7 +267,7 @@ public ReflectionAuditingBeanWrapper(ConversionService conversionService, T targ
 		}
 
 		@Override
-		public Object setCreatedBy(Object value) {
+		public Object setCreatedBy(@Nullable Object value) {
 			return setField(metadata.getCreatedByField(), value);
 		}
 
@@ -277,7 +277,7 @@ public TemporalAccessor setCreatedDate(TemporalAccessor value) {
 		}
 
 		@Override
-		public Object setLastModifiedBy(Object value) {
+		public Object setLastModifiedBy(@Nullable Object value) {
 			return setField(metadata.getLastModifiedByField(), value);
 		}
 
@@ -308,7 +308,8 @@ public T getBean() {
 		 * @param field
 		 * @param value
 		 */
-		private <S> S setField(Optional<Field> field, S value) {
+		@Nullable
+		private <S> S setField(Optional<Field> field, @Nullable S value) {
 
 			field.ifPresent(it -> ReflectionUtils.setField(it, target, value));
 

src/main/java/org/springframework/data/auditing/MappingAuditableBeanWrapperFactory.java

@@ -40,6 +40,8 @@
 import org.springframework.data.mapping.context.MappingContext;
 import org.springframework.data.mapping.context.PersistentEntities;
 import org.springframework.data.util.Lazy;
+import org.springframework.lang.Contract;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -203,7 +205,7 @@ public TemporalAccessor setCreatedDate(TemporalAccessor value) {
 		}
 
 		@Override
-		public Object setLastModifiedBy(Object value) {
+		public Object setLastModifiedBy(@Nullable Object value) {
 			return setProperty(metadata.lastModifiedByPaths, value);
 		}
 
@@ -226,8 +228,10 @@ public T getBean() {
 			return accessor.getBean();
 		}
 
+		@Nullable
+		@Contract("_, null -> null; _, !null -> !null")
 		private <S> S setProperty(
-				PersistentPropertyPaths<?, ? extends PersistentProperty<?>> paths, S value) {
+				PersistentPropertyPaths<?, ? extends PersistentProperty<?>> paths, @Nullable S value) {
 
 			paths.forEach(it -> this.accessor.setProperty(it, value, OPTIONS));