@Override
    protected Procedure<BasicProcedureEnv>[] execute(BasicProcedureEnv env)
      throws ProcedureYieldException, InterruptedException {
      return new Procedure[] { this };
    }
A do-nothing basic procedure just for testing toString.
hbase-procedure/src/test/java/org/apache/hadoop/hbase/procedure2/TestProcedureToString.java