DATACMNS-1364 - Store persistent properties in HashMap.

We now use HashMap to store persistent properties of a PersistentEntity. An entity is built in a single thread so no concurrent modification happens. Concurrent reads may happen during entity usage which is fine as the PersistentEntity is not changed anymore. Previously, we used ConcurrentReferenceHashMap defaulting to soft references. Soft references can be cleared at the discretion of the GC in response to memory demand. So a default ConcurrentReferenceHashMap is memory-sensitive and acts like a cache with memory-based eviction rules.

Persistent properties are not subject to be cached but elements of a PersistentEntity and cannot be recovered once cleared.

Original pull request: #304.

Author: mp911de

Diff for: src/main/java/org/springframework/data/mapping/model/BasicPersistentEntity.java

@@ -31,7 +31,8 @@
 import org.springframework.data.util.TypeInformation;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
-import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.CollectionUtils;
+import org.springframework.util.ConcurrentReferenceHashMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
 
@@ -95,8 +96,8 @@ public BasicPersistentEntity(TypeInformation<T> information, @Nullable Comparato
 		this.associations = comparator == null ? new HashSet<>() : new TreeSet<>(new AssociationComparator<>(comparator));
 
 		this.propertyCache = new HashMap<>();
-		this.annotationCache = new HashMap<>();
-		this.propertyAnnotationCache = new LinkedMultiValueMap<>();
+		this.annotationCache = new ConcurrentReferenceHashMap<>();
+		this.propertyAnnotationCache = CollectionUtils.toMultiValueMap(new ConcurrentReferenceHashMap<>());
 		this.propertyAccessorFactory = BeanWrapperPropertyAccessorFactory.INSTANCE;
 		this.typeAlias = Lazy.of(() -> getAliasFromAnnotation(getType()));
 	}

Diff for: src/test/java/org/springframework/data/mapping/model/BasicPersistentEntityUnitTests.java

@@ -126,24 +126,27 @@ public void considersComparatorForPropertyOrder() {
 		assertThat(entity.getPersistentProperty("ssn")).isEqualTo(iterator.next());
 	}
 
-	@Test // DATACMNS-186
+	@Test // DATACMNS-18, DATACMNS-1364
 	public void addingAndIdPropertySetsIdPropertyInternally() {
 
 		MutablePersistentEntity<Person, T> entity = createEntity(Person.class);
 		assertThat(entity.getIdProperty()).isNull();
 
+		when(property.getName()).thenReturn("id");
 		when(property.isIdProperty()).thenReturn(true);
 		entity.addPersistentProperty(property);
 		assertThat(entity.getIdProperty()).isEqualTo(property);
 	}
 
-	@Test // DATACMNS-186
+	@Test // DATACMNS-186, DATACMNS-1364
 	public void rejectsIdPropertyIfAlreadySet() {
 
 		MutablePersistentEntity<Person, T> entity = createEntity(Person.class);
 
+		when(property.getName()).thenReturn("id");
 		when(property.isIdProperty()).thenReturn(true);
 		when(anotherProperty.isIdProperty()).thenReturn(true);
+		when(anotherProperty.getName()).thenReturn("another");
 
 		entity.addPersistentProperty(property);
 		exception.expect(MappingException.class);
@@ -331,7 +334,7 @@ static class PersistableEntity implements Persistable<Long> {
 
 		private final Long id = 42L;
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.data.domain.Persistable#getId()
 		 */
@@ -340,7 +343,7 @@ public Long getId() {
 			return 4711L;
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.data.domain.Persistable#isNew()
 		 */