@Override
  protected void rollback(final TEnvironment env) {
    throw new UnsupportedOperationException();
  }
Special procedure used as a chore. Instead of bringing the Chore class in (dependencies reason),
we reuse the executor timeout thread for this special case. The assumption is that procedure is
used as hook to dispatch other procedures or trigger some cleanups. It does not store state in
the ProcedureStore. this is just for in-memory chore executions.
hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/ProcedureInMemoryChore.java