protected void completionCleanup(TEnvironment env) {
    // no-op
  }
Called when the procedure is marked as completed (success or rollback). The procedure
implementor may use this method to cleanup in-memory states. This operation will not be retried
on failure. If a procedure took a lock, it will have been released when this method runs.
hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/Procedure.java