@RestrictedApi(explanation = "Should only be called in tests", link = "",
      allowedOnPath = ".*/src/test/.*")
  public boolean setUseExecutor(final boolean useExecutor) {
    boolean oldSetting = this.useExecutor;
    this.useExecutor = useExecutor;
    return oldSetting;
  }
CompactedHFilesDischarger runs asynchronously by default using the hosting RegionServer's
Executor. In tests it can be useful to force a synchronous cleanup. Use this method to set
no-executor before you call run.
@return The old setting for <code>useExecutor</code>
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/CompactedHFilesDischarger.java