Xtext editor throws java.lang.IllegalStateException on touching files outside of eclipse workspace

Steps to reproduce

1. Import org.eclipse.xtext.example.arithmetics example project.
2. Launch the project and create sample.calc dsl file with below content
   
3. Write a batch script which recursively touch sample.calc file outside of eclipse workspace.
   

     :loop
      copy /b sample.calc +,,
     goto loop
   

4. Open sample.calc in Xtext editor
5. IllegalState exception is thrown below is the stacktrace for same

Analysis :

• When ever the resource is changed within editor. XtextEditor triggers a firePropertyChange(int).
• Editor sees the resource which has changed is dirty and calls the DirtyStateManager.discardDirtyState(IDirtyResource).
• Internally calls PersistentDataAwareDirtyResource(DocumentBasedDirtyResource).getURI().
• For the dirty resource org.eclipse.xtext.ui.editor.DocumentBasedDirtyResource.initiallyProcessResource(XtextResource) does not get the description and finally throws exception as the description is null.

stacktrace :

      java.lang.IllegalStateException: Cannot use getURI if this dirty resource is currently not initialized
	at org.eclipse.xtext.ui.editor.DocumentBasedDirtyResource.getURI(DocumentBasedDirtyResource.java:129)
	at org.eclipse.xtext.ui.editor.DirtyStateEditorSupport$ClientAwareDirtyResource.getURI(DirtyStateEditorSupport.java:299)
	at org.eclipse.xtext.ui.editor.DirtyStateManager.discardDirtyState(DirtyStateManager.java:63)
	at org.eclipse.xtext.ui.editor.DirtyStateEditorSupport.markEditorClean(DirtyStateEditorSupport.java:477)
	at org.eclipse.xtext.ui.editor.XtextEditor$1.propertyChanged(XtextEditor.java:208)
	at org.eclipse.ui.part.WorkbenchPart.firePropertyChange(WorkbenchPart.java:124)
	at org.eclipse.ui.texteditor.AbstractTextEditor.firePropertyChange(AbstractTextEditor.java:6339)
	at org.eclipse.ui.texteditor.AbstractTextEditor$ElementStateListener.lambda$1(AbstractTextEditor.java:445)
	at org.eclipse.ui.texteditor.AbstractTextEditor$ElementStateListener.execute(AbstractTextEditor.java:587)
	at org.eclipse.ui.texteditor.AbstractTextEditor$ElementStateListener.elementDirtyStateChanged(AbstractTextEditor.java:447)
	at org.eclipse.ui.texteditor.AbstractDocumentProvider.fireElementDirtyStateChanged(AbstractDocumentProvider.java:664)
	at org.eclipse.ui.editors.text.FileDocumentProvider.handleElementContentChanged(FileDocumentProvider.java:820)
	at org.eclipse.ui.editors.text.FileDocumentProvider$FileSynchronizer$2.execute(FileDocumentProvider.java:260)
	at org.eclipse.ui.editors.text.FileDocumentProvider$SafeChange.run(FileDocumentProvider.java:150)
	at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:40)
	at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:185)
	at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3987)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3615)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1157)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1046)
	at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:155)
	at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:644)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:551)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:153)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:150)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:203)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:401)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:255)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:657)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:594)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1465)
	at org.eclipse.equinox.launcher.Main.main(Main.java:1438)        
    ``` 
       

 

Reproduce the failure with the org.eclipse.xtext.example.arithmetics project, an externally touched sample.calc file, and the provided batch script. Start with DocumentBasedDirtyResource.initiallyProcessResource and getURI, then trace DirtyStateManager.discardDirtyState through DirtyStateEditorSupport and XtextEditor. Done means repeatedly touching the file outside the workspace no longer throws IllegalStateException.