protected void afterExec(TEnvironment env) {
    // no-op
  }
Called after we call the execute method of this procedure, and also after we initialize all the
sub procedures and persist the the state if persistence is needed.
<p>
This is for doing some hooks after we initialize the sub procedures. See HBASE-29259 for more
details on why we can not release the region lock inside the execute method.
hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/Procedure.java