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src/main/java/org/jenkinsci/plugins/workflow/job/AbstractItemDescriptor.java

@@ -0,0 +1,15 @@
+package org.jenkinsci.plugins.workflow.job;
+
+import hudson.util.FormValidation;
+import jenkins.model.Jenkins;
+import org.kohsuke.accmod.Restricted;
+import org.kohsuke.accmod.restrictions.NoExternalUse;
+import org.kohsuke.stapler.AncestorInPath;
+import org.kohsuke.stapler.QueryParameter;
+
+public interface AbstractItemDescriptor {
+    @Restricted(NoExternalUse.class)
+    public default FormValidation doCheckDisplayNameOrNull(@AncestorInPath WorkflowJob job, @QueryParameter String value) {
+        return Jenkins.get().doCheckDisplayName(value, job.getName());
+    }
+}

src/main/java/org/jenkinsci/plugins/workflow/job/WorkflowJob.java

@@ -69,6 +69,7 @@
 import hudson.triggers.TriggerDescriptor;
 import hudson.util.AlternativeUiTextProvider;
 import hudson.util.DescribableList;
+import hudson.util.FormValidation;
 import hudson.widgets.HistoryWidget;
 import java.io.File;
 import java.io.IOException;
@@ -98,12 +99,14 @@
 import org.kohsuke.accmod.Restricted;
 import org.kohsuke.accmod.restrictions.DoNotUse;
 import org.kohsuke.accmod.restrictions.NoExternalUse;
+import org.kohsuke.stapler.AncestorInPath;
+import org.kohsuke.stapler.QueryParameter;
 import org.kohsuke.stapler.StaplerRequest;
 import org.kohsuke.stapler.StaplerResponse;
 import org.kohsuke.stapler.export.Exported;
 
 @SuppressWarnings({"unchecked", "rawtypes"})
-public final class WorkflowJob extends Job<WorkflowJob,WorkflowRun> implements LazyBuildMixIn.LazyLoadingJob<WorkflowJob,WorkflowRun>, ParameterizedJobMixIn.ParameterizedJob<WorkflowJob, WorkflowRun>, TopLevelItem, Queue.FlyweightTask, SCMTriggerItem, BlockableResume {
+public final class WorkflowJob extends Job<WorkflowJob,WorkflowRun> implements LazyBuildMixIn.LazyLoadingJob<WorkflowJob,WorkflowRun>, ParameterizedJobMixIn.ParameterizedJob<WorkflowJob, WorkflowRun>, TopLevelItem, Queue.FlyweightTask, SCMTriggerItem, BlockableResume, AbstractItemDescriptor {
 
     private static final Logger LOGGER = Logger.getLogger(WorkflowJob.class.getName());
 
@@ -193,7 +196,6 @@ public void setDefinition(FlowDefinition definition) {
         getTriggersJobProperty().startTriggers(Items.currentlyUpdatingByXml());
     }
 
-
     @Override public void addProperty(JobProperty jobProp) throws IOException {
         super.addProperty(jobProp);
         if (jobProp instanceof PipelineTriggersJobProperty) {
@@ -254,6 +256,7 @@ public void setDefinition(FlowDefinition definition) {
         return buildMixIn.getEstimatedDurationCandidates();
     }
 
+
     @Override protected HistoryWidget createHistoryWidget() {
         return buildMixIn.createHistoryWidget();
     }