DATAMONGO-2168 - Polishing.

MetadataBackedField no longer fails when Path detects reference to field within java.lang.Class. This can happen when splitting the property name via camel case where the first part matches to class which resolves to the getClass() call on java.lang.Object. When then the 2nd part also maps to a method (like getName()) on Class an error would be thrown.

Original Pull Request: #631

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/QueryMapper.java

@@ -1028,6 +1028,11 @@ public class QueryMapper {
 			try {
 
 				PropertyPath path = PropertyPath.from(pathExpression.replaceAll("\\.\\d+", ""), entity.getTypeInformation());
+
+				if (isPathToJavaLangClassProperty(path)) {
+					return null;
+				}
+
 				PersistentPropertyPath<MongoPersistentProperty> propertyPath = mappingContext.getPersistentPropertyPath(path);
 
 				Iterator<MongoPersistentProperty> iterator = propertyPath.iterator();
@@ -1053,6 +1058,14 @@ public class QueryMapper {
 			}
 		}
 
+		private boolean isPathToJavaLangClassProperty(PropertyPath path) {
+
+			if (path.getType().equals(Class.class) && path.getLeafProperty().getOwningType().getType().equals(Class.class)) {
+				return true;
+			}
+			return false;
+		}
+
 		/**
 		 * Return the {@link Converter} to be used to created the mapped key. Default implementation will use
 		 * {@link PropertyToFieldNameConverter}.

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/QueryMapperUnitTests.java

@@ -810,6 +810,15 @@ public class QueryMapperUnitTests {
 		assertThat(mappedObject).containsEntry("className", "foo");
 	}
 
+	@Test // DATAMONGO-2168
+	public void getMappedObjectShouldIgnorePathsLeadingToJavaLangClassProperties/* like Class#getName() */() {
+
+		org.bson.Document update = new org.bson.Document("className", "foo");
+		org.bson.Document mappedObject = mapper.getMappedObject(update, context.getPersistentEntity(UserEntity.class));
+
+		assertThat(mappedObject).containsEntry("className", "foo");
+	}
+
 	@Document
 	public class Foo {
 		@Id private ObjectId id;
@@ -855,7 +864,7 @@ public class QueryMapperUnitTests {
 
 	class UserEntity {
 		String id;
-		List<String> publishers = new ArrayList<String>();
+		List<String> publishers = new ArrayList<>();
 	}
 
 	class CustomizedField {