Restore creation of plain HashSet/HashMap for direct HashSet/HashMap type

Closes gh-30596

Author: jhoeller

spring-core/src/main/java/org/springframework/core/CollectionFactory.java

@@ -179,7 +179,7 @@ public static <E> Collection<E> createCollection(Class<?> collectionType, int ca
 	@SuppressWarnings("unchecked")
 	public static <E> Collection<E> createCollection(Class<?> collectionType, @Nullable Class<?> elementType, int capacity) {
 		Assert.notNull(collectionType, "Collection type must not be null");
-		if (LinkedHashSet.class == collectionType || HashSet.class == collectionType ||
+		if (LinkedHashSet.class == collectionType ||
 				Set.class == collectionType || Collection.class == collectionType) {
 			return new LinkedHashSet<>(capacity);
 		}
@@ -197,6 +197,9 @@ else if (EnumSet.class.isAssignableFrom(collectionType)) {
 			Assert.notNull(elementType, "Cannot create EnumSet for unknown element type");
 			return EnumSet.noneOf(asEnumType(elementType));
 		}
+		else if (HashSet.class == collectionType) {
+			return new HashSet<>(capacity);
+		}
 		else {
 			if (collectionType.isInterface() || !Collection.class.isAssignableFrom(collectionType)) {
 				throw new IllegalArgumentException("Unsupported Collection type: " + collectionType.getName());
@@ -297,7 +300,7 @@ public static <K, V> Map<K, V> createMap(Class<?> mapType, int capacity) {
 	@SuppressWarnings({"rawtypes", "unchecked"})
 	public static <K, V> Map<K, V> createMap(Class<?> mapType, @Nullable Class<?> keyType, int capacity) {
 		Assert.notNull(mapType, "Map type must not be null");
-		if (LinkedHashMap.class == mapType || HashMap.class == mapType || Map.class == mapType) {
+		if (LinkedHashMap.class == mapType || Map.class == mapType) {
 			return new LinkedHashMap<>(capacity);
 		}
 		else if (LinkedMultiValueMap.class == mapType || MultiValueMap.class == mapType) {
@@ -310,6 +313,9 @@ else if (EnumMap.class == mapType) {
 			Assert.notNull(keyType, "Cannot create EnumMap for unknown key type");
 			return new EnumMap(asEnumType(keyType));
 		}
+		else if (HashMap.class == mapType) {
+			return new HashMap<>(capacity);
+		}
 		else {
 			if (mapType.isInterface() || !Map.class.isAssignableFrom(mapType)) {
 				throw new IllegalArgumentException("Unsupported Map type: " + mapType.getName());

spring-core/src/test/java/org/springframework/core/CollectionFactoryTests.java

@@ -217,15 +217,15 @@ void createsCollectionsCorrectly() {
 
 		// concrete types
 		testCollection(ArrayList.class, ArrayList.class);
-		testCollection(HashSet.class, LinkedHashSet.class);
+		testCollection(HashSet.class, HashSet.class);
 		testCollection(LinkedHashSet.class, LinkedHashSet.class);
 		testCollection(TreeSet.class, TreeSet.class);
 	}
 
 	private void testCollection(Class<?> collectionType, Class<?> resultType) {
 		assertThat(CollectionFactory.isApproximableCollectionType(collectionType)).isTrue();
-		assertThat(createCollection(collectionType, 0)).isInstanceOf(resultType);
-		assertThat(createCollection(collectionType, String.class, 0)).isInstanceOf(resultType);
+		assertThat(createCollection(collectionType, 0)).isExactlyInstanceOf(resultType);
+		assertThat(createCollection(collectionType, String.class, 0)).isExactlyInstanceOf(resultType);
 	}
 
 	@Test
@@ -266,16 +266,16 @@ void createsMapsCorrectly() {
 		testMap(MultiValueMap.class, LinkedMultiValueMap.class);
 
 		// concrete types
-		testMap(HashMap.class, LinkedHashMap.class);
+		testMap(HashMap.class, HashMap.class);
 		testMap(LinkedHashMap.class, LinkedHashMap.class);
 		testMap(TreeMap.class, TreeMap.class);
 		testMap(LinkedMultiValueMap.class, LinkedMultiValueMap.class);
 	}
 
 	private void testMap(Class<?> mapType, Class<?> resultType) {
 		assertThat(CollectionFactory.isApproximableMapType(mapType)).isTrue();
-		assertThat(createMap(mapType, 0)).isInstanceOf(resultType);
-		assertThat(createMap(mapType, String.class, 0)).isInstanceOf(resultType);
+		assertThat(createMap(mapType, 0)).isExactlyInstanceOf(resultType);
+		assertThat(createMap(mapType, String.class, 0)).isExactlyInstanceOf(resultType);
 	}
 
 	@Test