Estoy desarrollando un Plugin Eclipse. Dentro de mi plugin tengo el siguiente código:

Bundle bundle = Platform.getBundle("org.eclipse.acceleo.EcoreDiff2EDelta");
URL fileURL = bundle.getEntry("src/metamodel/EcoreDiff.ecore");
String uri = null;
try {
        uri = FileLocator.resolve(fileURL).getFile();
    } catch (IOException e1) {
        e1.printStackTrace();
    }

    Resource resource = resourceSet.getResource(URI.createURI(uri), true);

Este código accede a un recurso (EcoreDiff.ecore) que reside dentro de mi complemento, en la carpeta src / metamodel. Cuando ejecuto el complemento haciendo clic derecho en la carpeta del proyecto -> ejecutar como -> aplicación eclipse todo funciona bien. Pero si exporto el complemento como "complemento desplegable y fragmentos" obtengo el seguimiento de pila que sigue, lo que básicamente significa que no pudo encontrar el archivo EcoreDiff.ecore. He estado tratando de arreglar esto por dos días, no entiendo qué está mal ...

java.lang.reflect.InvocationTargetException
at org.eclipse.jface.operation.ModalContext.run(ModalContext.java:421)
at org.eclipse.jface.dialogs.ProgressMonitorDialog.run(ProgressMonitorDialog.java:507)
at org.eclipse.ui.internal.progress.ProgressMonitorJobsDialog.run(ProgressMonitorJobsDialog.java:275)
at org.eclipse.ui.internal.progress.ProgressManager$3.run(ProgressManager.java:960)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.ui.internal.progress.ProgressManager.busyCursorWhile(ProgressManager.java:995)
at org.eclipse.ui.internal.progress.ProgressManager.busyCursorWhile(ProgressManager.java:970)
at org.eclipse.ui.internal.progress.ProgressManager.run(ProgressManager.java:1166)
at org.eclipse.acceleo.EcoreDiff2EDelta.ui.popupMenus.AcceleoGenerateEcoreDiff2EDeltaAction.run(AcceleoGenerateEcoreDiff2EDeltaAction.java:91)
at org.eclipse.ui.actions.ActionDelegate.runWithEvent(ActionDelegate.java:70)
at org.eclipse.ui.internal.PluginAction.runWithEvent(PluginAction.java:241)
at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:584)
at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:501)
at org.eclipse.jface.action.ActionContributionItem$5.handleEvent(ActionContributionItem.java:411)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4169)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3758)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1022)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:916)
at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:86)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:585)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:540)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:124)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:353)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:180)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:629)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:584)
at org.eclipse.equinox.launcher.Main.run(Main.java:1438)
at org.eclipse.equinox.launcher.Main.main(Main.java:1414)
Caused by: java.lang.NullPointerException
at org.eclipse.core.internal.runtime.Activator.getURLConverter(Activator.java:321)
at org.eclipse.core.runtime.FileLocator.resolve(FileLocator.java:227)
at org.eclipse.acceleo.EcoreDiff2EDelta.main.Generate.registerPackages(Generate.java:359)
at org.eclipse.acceleo.engine.service.AbstractAcceleoGenerator.initialize(AbstractAcceleoGenerator.java:422)
at org.eclipse.acceleo.EcoreDiff2EDelta.main.Generate.<init>(Generate.java:97)
at org.eclipse.acceleo.EcoreDiff2EDelta.ui.common.GenerateAll.doGenerate(GenerateAll.java:90)
at org.eclipse.acceleo.EcoreDiff2EDelta.ui.popupMenus.AcceleoGenerateEcoreDiff2EDeltaAction$1.run(AcceleoGenerateEcoreDiff2EDeltaAction.java:76)
at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:121)
Root exception:
java.lang.NullPointerException
at org.eclipse.core.internal.runtime.Activator.getURLConverter(Activator.java:321)
at org.eclipse.core.runtime.FileLocator.resolve(FileLocator.java:227)
at org.eclipse.acceleo.EcoreDiff2EDelta.main.Generate.registerPackages(Generate.java:359)
at org.eclipse.acceleo.engine.service.AbstractAcceleoGenerator.initialize(AbstractAcceleoGenerator.java:422)
at org.eclipse.acceleo.EcoreDiff2EDelta.main.Generate.<init>(Generate.java:97)
at org.eclipse.acceleo.EcoreDiff2EDelta.ui.common.GenerateAll.doGenerate(GenerateAll.java:90)
at org.eclipse.acceleo.EcoreDiff2EDelta.ui.popupMenus.AcceleoGenerateEcoreDiff2EDeltaAction$1.run(AcceleoGenerateEcoreDiff2EDeltaAction.java:76)
at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:121)