DATACMNS-1828 - Fix Map component type lookup for custom Map implementations.

Instead of using the first generic type parameter of a parameterized type as Map component type, we now explicitly lookup the super type's Map-specific generics configuration and use its first generic type parameter. The same for collection like types falling back to the parameter type bound to Iterable.

Author: odrotbohm

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

@@ -156,6 +156,17 @@ public boolean isAssignableFrom(TypeInformation<?> target) {
 	@Override
 	@Nullable
 	protected TypeInformation<?> doGetComponentType() {
+
+		boolean isCustomMapImplementation = isMap() && !getType().equals(Map.class);
+
+		if (isCustomMapImplementation) {
+			return getRequiredSuperTypeInformation(Map.class).getComponentType();
+		}
+
+		if (isCollectionLike() && !getType().getPackage().getName().startsWith("java.")) {
+			return getRequiredSuperTypeInformation(Iterable.class).getComponentType();
+		}
+
 		return createInfo(type.getActualTypeArguments()[0]);
 	}
 

src/test/java/org/springframework/data/repository/util/QueryExecutionConvertersUnitTests.java

@@ -264,8 +264,8 @@ void unwrapsPages() throws Exception {
 		Method method = Sample.class.getMethod("pages");
 		TypeInformation<Object> returnType = ClassTypeInformation.fromReturnTypeOf(method);
 
-		assertThat(QueryExecutionConverters.unwrapWrapperTypes(returnType))
-				.isEqualTo(ClassTypeInformation.from(String.class));
+		assertThat(QueryExecutionConverters.unwrapWrapperTypes(returnType).getType())
+				.isEqualTo(String.class);
 	}
 
 	@Test // DATACMNS-983

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

@@ -443,6 +443,32 @@ public void mergesGenericsFromContextAndProvidedDefaultOnSpecialization() {
 		assertThat(specialized.getProperty("root").getType()).isEqualTo(Aggregate.class);
 	}
 
+	@Test // DATACMNS-1828
+	void discoversMapKeyAndValueTypeFromTypedMap() {
+
+		TypeInformation<TypeWithTypedMap> information = from(TypeWithTypedMap.class);
+
+		TypeInformation<?> typedMap = information.getProperty("typedMap");
+
+		assertThat(typedMap.getType()).isEqualTo(StringKeyMap.class);
+		assertThat(typedMap.isMap()).isTrue();
+		assertThat(typedMap.getRequiredComponentType().getType()).isEqualTo(String.class);
+		assertThat(typedMap.getMapValueType().getType()).isEqualTo(Long.class);
+
+		TypeInformation<?> longMultiValueMap = information.getProperty("longMultiValueMap");
+
+		assertThat(longMultiValueMap.getType()).isEqualTo(MultiValueMap.class);
+		assertThat(longMultiValueMap.getRequiredComponentType().getType()).isEqualTo(String.class);
+		assertThat(longMultiValueMap.getMapValueType().getType()).isEqualTo(List.class);
+		assertThat(longMultiValueMap.getMapValueType().getRequiredActualType().getType()).isEqualTo(Long.class);
+
+		TypeInformation<?> justMap = information.getProperty("justMap");
+
+		assertThat(justMap.getType()).isEqualTo(Map.class);
+		assertThat(justMap.getRequiredComponentType().getType()).isEqualTo(String.class);
+		assertThat(justMap.getMapValueType().getType()).isEqualTo(Long.class);
+	}
+
 	static class StringMapContainer extends MapContainer<String> {
 
 	}
@@ -681,4 +707,15 @@ static class OfferCreated extends DomainEvent<OfferDetails, Long> {}
 
 	// A domain type partially binding generics
 	static class GenericEvent<T extends Aggregate> extends DomainEvent<T, Long> {}
+
+	// DATACMNS-1828
+	interface StringKeyMap<T> extends Map<String, T> {}
+
+	interface MultiValueMap<T> extends Map<String, List<T>> {}
+
+	static class TypeWithTypedMap {
+		StringKeyMap<Long> typedMap;
+		MultiValueMap<Long> longMultiValueMap;
+		Map<String, Long> justMap;
+	}
 }