DATAMONGO-1646 - Polishing.

Add missing license header.

Original Pull Request: #481

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/City.java

@@ -1,8 +1,27 @@
+/*
+ * Copyright 2017 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.springframework.data.mongodb.core.aggregation;
 
 import lombok.AllArgsConstructor;
 import lombok.NoArgsConstructor;
 
+/**
+ * @author Thomas Darimont
+ * @author Mark Paluch
+ */
 @lombok.Data
 @AllArgsConstructor
 @NoArgsConstructor