protected synchronized boolean isValid() {
    if (subprocStack != null) {
      for (Procedure<TEnvironment> proc : subprocStack) {
        if (proc == null) {
          return false;
        }
      }
    }
    return true;
  }
Called on store load by the ProcedureExecutor to validate the procedure stack.
hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/RootProcedureState.java