code: private ExecutionMessage createPendingExecutionMessage(Execution nextStepExecution) {
          // Take care of worker group
          String groupName = nextStepExecution.getGroupName();
          if (groupName == null) {
              groupName = WorkerNode.DEFAULT_WORKER_GROUPS[0];
          }
          return new ExecutionMessage(ExecutionMessage.EMPTY_EXEC_STATE_ID,
                  ExecutionMessage.EMPTY_WORKER,
                  groupName,
                  executionMessage.getMsgId(),
                  ExecStatus.PENDING,
                  converter.createPayload(nextStepExecution),
                  0).setWorkerKey(executionMessage.getWorkerKey());
      }
docs: Creates pending execution message for the next step, base on current execution message