Github user bowenli86 commented on the issue: https://github.com/apache/flink/pull/5112 @StephanEwen Thanks Stephan. To your comments: 1. in order to have `experiemental/scala` package in `flink-streaming-scala`, I have to make `DataStreamUtils` its own class to avoid package name collisions with `scala` 2. I don't think checkstyle of the whole project`flink-streaming-scala` is active. I did some tests which removed comments and left unused class imports, the build still passed. I think we should address enabling checkstyle separately, may need to reopen[FLINK-6902]( https://issues.apache.org/jira/browse/FLINK-6902). cc @zentol
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