DATACMNS-440 - Fixed map value type resolving for Map value types.

Previously the map value type resolving algorithm checked the value type to be of type Map again to shortcut the resolution. We now weakened this to an assignment check and eagerly resolve the generic type if its bound on exactly that level already. If no concrete type argument can be found, we fall back to the general generics resolution mechanism.

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

@@ -56,9 +56,13 @@ public ParameterizedTypeInformation(ParameterizedType type, TypeDiscoverer<?> pa
 	@SuppressWarnings("deprecation")
 	public TypeInformation<?> getMapValueType() {
 
-		if (Map.class.equals(getType())) {
+		if (Map.class.isAssignableFrom(getType())) {
+
 			Type[] arguments = type.getActualTypeArguments();
-			return createInfo(arguments[1]);
+
+			if (arguments.length > 1) {
+				return createInfo(arguments[1]);
+			}
 		}
 
 		Class<?> rawType = getType();

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

@@ -25,6 +25,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.SortedMap;
 
 import org.hamcrest.Matchers;
 import org.junit.Test;
@@ -296,6 +297,26 @@ public void returnsNullForRawTypesOnly() {
 		assertThat(from(MyIterable.class).getComponentType(), is(notNullValue()));
 	}
 
+	/**
+	 * @see DATACMNS-440
+	 */
+	@Test
+	public void detectsSpecialMapAsMapValueType() {
+
+		TypeInformation<SuperGenerics> information = ClassTypeInformation.from(SuperGenerics.class);
+
+		TypeInformation<?> propertyInformation = information.getProperty("seriously");
+		assertThat(propertyInformation.getType(), is((Object) SortedMap.class));
+
+		TypeInformation<?> mapValueType = propertyInformation.getMapValueType();
+		assertThat(mapValueType.getType(), is((Object) SortedMap.class));
+		assertThat(mapValueType.getComponentType().getType(), is((Object) String.class));
+
+		TypeInformation<?> nestedValueType = mapValueType.getMapValueType();
+		assertThat(nestedValueType.getType(), is((Object) List.class));
+		assertThat(nestedValueType.getComponentType().getType(), is((Object) Person.class));
+	}
+
 	static class StringMapContainer extends MapContainer<String> {
 
 	}
@@ -425,4 +446,9 @@ interface Identifiable {
 	interface MyRawIterable extends Iterable {}
 
 	interface MyIterable<T> extends Iterable<T> {}
+
+	static class SuperGenerics {
+
+		SortedMap<String, ? extends SortedMap<String, List<Person>>> seriously;
+	}
 }