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nothing else to do.
Rejected Alternatives
change SplitFetcher to a public Interface
If SplitFetcherManager becomes PublicEvolving, that also means SplitFetcher needs to be PublicEvolving, because it is returned by the protected method SplitFetcherManagerIf SplitFetcherManager becomes PublicEvolving, that also means SplitFetcher needs to be PublicEvolving, because it is returned by the protected method SplitFetcherManager.createSplitFetcher()
However, SplitFetcher requires FutureCompletingBlockingQueue as a constructor parameter. SplitFetcher is a class rather than Interface. Therefore, I want to change SplitFetcher to a public Interface and moving its implementation details to an implement subclass .
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