Fix the NPE of DolphinSchedulerAppConnLinkisJob.

Author: wushengyeyouya

plugins/dolphinscheduler/dss-dolphinscheduler-client/src/main/scala/com/webank/wedatasphere/dss/plugins/dolphinscheduler/linkis/client/job/DolphinSchedulerAppConnLinkisJob.scala

@@ -2,9 +2,11 @@ package com.webank.wedatasphere.dss.plugins.dolphinscheduler.linkis.client.job
 
 import com.webank.wedatasphere.dss.linkis.node.execution.job.AbstractAppConnLinkisJob
 import com.webank.wedatasphere.dss.plugins.dolphinscheduler.linkis.client.conf.LinkisJobTypeConf
+import org.apache.commons.lang3.StringUtils
 
 class DolphinSchedulerAppConnLinkisJob extends AbstractAppConnLinkisJob {
-  override def getSubmitUser: String = if (getJobProps.get(LinkisJobTypeConf.FLOW_SUBMIT_USER).isEmpty) getJobProps.get(LinkisJobTypeConf.PROXY_USER) else getJobProps.get(LinkisJobTypeConf.FLOW_SUBMIT_USER)
+  override def getSubmitUser: String = if (StringUtils.isBlank(getJobProps.get(LinkisJobTypeConf.FLOW_SUBMIT_USER)))
+    getJobProps.get(LinkisJobTypeConf.PROXY_USER) else getJobProps.get(LinkisJobTypeConf.FLOW_SUBMIT_USER)
 
   override def getUser: String = getJobProps.get(LinkisJobTypeConf.PROXY_USER)