DATACMNS-855 - Prevent memory leak in SyntheticParameterizedType.

Added proper equals(…) and hashCode() methods to SyntheticParameterizedType to make sure instances created for the same type information and type parameters are considered equal.

src/main/java/org/springframework/data/util/TypeDiscoverer.java

@@ -15,6 +15,10 @@
  */
 package org.springframework.data.util;
 
+import lombok.EqualsAndHashCode;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
+
 import java.beans.PropertyDescriptor;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Field;
@@ -558,23 +562,12 @@ class TypeDiscoverer<S> implements TypeInformation<S> {
 	 * @author Oliver Gierke
 	 * @since 1.11
 	 */
+	@EqualsAndHashCode
+	@RequiredArgsConstructor
 	private static class SyntheticParamterizedType implements ParameterizedType {
 
-		private final ClassTypeInformation<?> typeInformation;
-		private final List<TypeInformation<?>> typeParameters;
-
-		/**
-		 * @param typeInformation must not be {@literal null}.
-		 * @param typeParameters must not be {@literal null}.
-		 */
-		public SyntheticParamterizedType(ClassTypeInformation<?> typeInformation, List<TypeInformation<?>> typeParameters) {
-
-			Assert.notNull(typeInformation, "Type must not be null!");
-			Assert.notNull(typeParameters, "Type parameters must not be null!");
-
-			this.typeInformation = typeInformation;
-			this.typeParameters = typeParameters;
-		}
+		private final @NonNull ClassTypeInformation<?> typeInformation;
+		private final @NonNull List<TypeInformation<?>> typeParameters;
 
 		/*
 		 * (non-Javadoc)

src/test/java/org/springframework/data/util/ClassTypeInformationUnitTests.java

@@ -382,6 +382,24 @@ public class ClassTypeInformationUnitTests {
 		assertThat(property.specialize(from), is((TypeInformation) from));
 	}
 
+	/**
+	 * @see DATACMNS-855
+	 */
+	@Test
+	@SuppressWarnings("rawtypes")
+	public void specializedTypeEqualsAndHashCode() {
+
+		ClassTypeInformation<Foo> root = ClassTypeInformation.from(Foo.class);
+		TypeInformation<?> property = root.getProperty("abstractBar");
+
+		TypeInformation left = property.specialize(ClassTypeInformation.from(Bar.class));
+		TypeInformation right = property.specialize(ClassTypeInformation.from(Bar.class));
+
+		assertThat(left, is(right));
+		assertThat(right, is(left));
+		assertThat(left.hashCode(), is(right.hashCode()));
+	}
+
 	static class StringMapContainer extends MapContainer<String> {
 
 	}