Github user tony810430 commented on a diff in the pull request: https://github.com/apache/flink/pull/5115#discussion_r154913437 --- Diff: flink-runtime/src/main/java/org/apache/flink/runtime/metrics/groups/AbstractMetricGroup.java --- @@ -409,6 +404,22 @@ public MetricGroup addGroup(String name) { return addGroup(name, false); } + @Override + public MetricGroup addGroup(String key, String value) { --- End diff -- Sorry for the last incorrect comment. This change will make `GenerciMetricGroup` always create `GenericKeyMetricGroup`, because I also change the behavior of `#AbstractMetricGroup#createChildGroup(String name)`. It seems there is a bug in `MetricGroupTest#alwaysCanCreateGenericMetricGroup`, because what I want is always return exactly `GenericMetricGroup` and child class is unacceptable.
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