Github user tillrohrmann commented on a diff in the pull request: https://github.com/apache/flink/pull/4757#discussion_r148606465 --- Diff: flink-runtime/src/main/java/org/apache/flink/runtime/rest/messages/metrics/MetricsOverview.java --- @@ -0,0 +1,40 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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.apache.flink.runtime.rest.messages.metrics; + +import org.apache.flink.runtime.rest.messages.ResponseBody; + +import java.util.ArrayList; +import java.util.Collection; + +/** + * Response of metrics handlers, represented as a list of {@link MetricEntry}. + */ +public class MetricsOverview extends ArrayList<MetricEntry> implements ResponseBody { --- End diff -- Let's not directly extend from `ArrayList` but instead use composition.
---