java.lang.IllegalStateException: Not expecting pod template to be null at this point
 	at org.csanchez.jenkins.plugins.kubernetes.KubernetesSlave.getTemplate(KubernetesSlave.java:92)
 	at org.csanchez.jenkins.plugins.kubernetes.pipeline.SecretsMasker$Factory.secretsOf(SecretsMasker.java:144)
 	at org.csanchez.jenkins.plugins.kubernetes.pipeline.SecretsMasker$Factory.get(SecretsMasker.java:122)
 	at org.csanchez.jenkins.plugins.kubernetes.pipeline.SecretsMasker$Factory.get(SecretsMasker.java:94)
 	at org.jenkinsci.plugins.workflow.steps.DynamicContext$Typed.get(DynamicContext.java:94)
 	at org.jenkinsci.plugins.workflow.cps.ContextVariableSet.get(ContextVariableSet.java:138)
 	at org.jenkinsci.plugins.workflow.cps.CpsThread.getContextVariable(CpsThread.java:135)
 	at org.jenkinsci.plugins.workflow.cps.CpsStepContext.doGet(CpsStepContext.java:297)
 	at org.jenkinsci.plugins.workflow.support.DefaultStepContext.get(DefaultStepContext.java:67)
 	at org.jenkinsci.plugins.workflow.support.DefaultStepContext.getListener(DefaultStepContext.java:116)
 	at org.jenkinsci.plugins.workflow.support.DefaultStepContext.get(DefaultStepContext.java:79)
 	at org.jenkinsci.plugins.workflow.support.DefaultStepContext.makeLauncher(DefaultStepContext.java:149)
 	at org.jenkinsci.plugins.workflow.support.DefaultStepContext.get(DefaultStepContext.java:75)
 	at org.jenkinsci.plugins.workflow.steps.durable_task.DurableTaskStep$Execution.launcher(DurableTaskStep.java:484) 

pipeline {
    agent {
        label 'jenkins-jx-base'
    }
    stages {
        stage('Restart Jenkins') {
            steps {
                container('jx-base') {
                    script {
                        sh 'kubectl delete pod -l app=jenkins --wait=false'
                    }
                    echo "restart OK"
                }
            }
        }
    }
}