DATACMNS-1364 - Polishing.

Use weak references in annotation and property annotation cache to retain references until the last GC root is cleared. Remove trailing whitespaces. Reformat.

Original pull request: #304.

Author: mp911de

src/main/java/org/springframework/data/mapping/model/BasicPersistentEntity.java

@@ -21,6 +21,7 @@
 import java.io.Serializable;
 import java.lang.annotation.Annotation;
 import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.stream.Collectors;
 
 import org.springframework.core.annotation.AnnotatedElementUtils;
@@ -38,6 +39,7 @@
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.ConcurrentReferenceHashMap;
+import org.springframework.util.ConcurrentReferenceHashMap.ReferenceType;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
 
@@ -105,8 +107,9 @@ public BasicPersistentEntity(TypeInformation<T> information, @Nullable Comparato
 		this.associations = comparator == null ? new HashSet<>() : new TreeSet<>(new AssociationComparator<>(comparator));
 
 		this.propertyCache = new ConcurrentHashMap<>();
-		this.annotationCache = new ConcurrentReferenceHashMap<>();
-		this.propertyAnnotationCache = CollectionUtils.toMultiValueMap(new ConcurrentReferenceHashMap<>());
+		this.annotationCache = new ConcurrentReferenceHashMap<>(16, ReferenceType.WEAK);
+		this.propertyAnnotationCache = CollectionUtils
+				.toMultiValueMap(new ConcurrentReferenceHashMap<>(16, ReferenceType.WEAK));
 		this.propertyAccessorFactory = BeanWrapperPropertyAccessorFactory.INSTANCE;
 		this.typeAlias = Lazy.of(() -> getAliasFromAnnotation(getType()));
 		this.isNewStrategy = Lazy.of(() -> Persistable.class.isAssignableFrom(information.getType()) //
@@ -236,7 +239,7 @@ public void addPersistentProperty(P property) {
 		}
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mapping.model.MutablePersistentEntity#setEvaluationContextProvider(org.springframework.data.spel.EvaluationContextProvider)
 	 */
@@ -469,7 +472,7 @@ public IdentifierAccessor getIdentifierAccessor(Object bean) {
 		return hasIdProperty() ? new IdPropertyIdentifierAccessor(this, bean) : new AbsentIdentifierAccessor(bean);
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mapping.PersistentEntity#isNew(java.lang.Object)
 	 */
@@ -481,7 +484,7 @@ public boolean isNew(Object bean) {
 		return isNewStrategy.get().isNew(bean);
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mapping.PersistentEntity#isImmutable()
 	 */
@@ -516,7 +519,7 @@ protected EvaluationContext getEvaluationContext(Object rootObject) {
 	 * Returns the default {@link IsNewStrategy} to be used. Will be a {@link PersistentEntityIsNewStrategy} by default.
 	 * Note, that this strategy only gets used if the entity doesn't implement {@link Persistable} as this indicates the
 	 * user wants to be in control over whether an entity is new or not.
-	 * 
+	 *
 	 * @return
 	 * @since 2.1
 	 */
@@ -526,7 +529,7 @@ protected IsNewStrategy getFallbackIsNewStrategy() {
 
 	/**
 	 * Verifies the given bean type to no be {@literal null} and of the type of the current {@link PersistentEntity}.
-	 * 
+	 *
 	 * @param bean must not be {@literal null}.
 	 */
 	private final void verifyBeanType(Object bean) {