default String getRunDate() {
        if(getVariables().containsKey("run_date")) {
            return (String) getVariables().get("run_date");
        } else {
            return null;
        }
    }
If the third-part AppConn has no project, and don't wants to integrate with DSS context service,
please use this class to asyncly execute refJob.
dss-standard/development-standard/development-process-standard-execution/src/main/java/com/webank/wedatasphere/dss/standard/app/development/listener/ref/RefExecutionRequestRef.java