Sometimes I get this when running swtbot tests, There is our class in stacktrace.
[java] !ENTRY org.eclipse.ui.navigator 4 0 2011-09-06 14:42:27.944 [java] !MESSAGE An exception occurred invoking extension: org.eclipse.jst.jee.ui.web for object P/BottomUpWS-web [java] !STACK 0 [java] java.lang.NullPointerException [java] at org.eclipse.jst.jee.model.internal.JEE5ModelProvider.createModelResource(JEE5ModelProvider.java:193) [java] at org.eclipse.jst.jee.model.internal.JEE5ModelProvider.getModelResource(JEE5ModelProvider.java:174) [java] at org.eclipse.jst.jee.model.internal.Web25ModelProvider.getModelObject(Web25ModelProvider.java:44) [java] at org.eclipse.jst.jee.model.internal.JEE5ModelProvider.getModelObject(JEE5ModelProvider.java:217) [java] at org.eclipse.jst.jee.model.internal.common.AbstractMergedModelProvider.getLastModificationTimeOfDDFile(AbstractMergedModelProvider.java:235) [java] at org.eclipse.jst.jee.model.internal.common.AbstractMergedModelProvider.hasToReloadModel(AbstractMergedModelProvider.java:229) [java] at org.eclipse.jst.jee.model.internal.common.AbstractMergedModelProvider.getMergedModel(AbstractMergedModelProvider.java:218) [java] at org.eclipse.jst.jee.model.internal.common.AbstractMergedModelProvider.getModelObject(AbstractMergedModelProvider.java:139) [java] at org.eclipse.jst.jee.ui.internal.navigator.Web25ContentProvider.getNewContentProviderInstance(Web25ContentProvider.java:69) [java] at org.eclipse.jst.jee.ui.internal.navigator.JEE5ContentProvider.getCachedContentProvider(JEE5ContentProvider.java:92) [java] at org.eclipse.jst.jee.ui.internal.navigator.Web25ContentProvider.getChildren(Web25ContentProvider.java:35) [java] at org.eclipse.ui.internal.navigator.extensions.SafeDelegateTreeContentProvider.getChildren(SafeDelegateTreeContentProvider.java:96) [java] at org.eclipse.ui.internal.navigator.extensions.SafeDelegateTreeContentProvider.getChildren(SafeDelegateTreeContentProvider.java:275) [java] at org.eclipse.ui.internal.navigator.extensions.SafeDelegateTreeContentProvider.getChildren(SafeDelegateTreeContentProvider.java:94) [java] at org.eclipse.ui.internal.navigator.NavigatorContentServiceContentProvider$1.run(NavigatorContentServiceContentProvider.java:152) [java] at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) [java] at org.eclipse.ui.internal.navigator.NavigatorContentServiceContentProvider.internalGetChildren(NavigatorContentServiceContentProvider.java:139) [java] at org.eclipse.ui.internal.navigator.NavigatorContentServiceContentProvider.getChildren(NavigatorContentServiceContentProvider.java:125) [java] at org.eclipse.jface.viewers.AbstractTreeViewer.getRawChildren(AbstractTreeViewer.java:1352) [java] at org.eclipse.jface.viewers.TreeViewer.getRawChildren(TreeViewer.java:391) [java] at org.eclipse.jface.viewers.StructuredViewer.getFilteredChildren(StructuredViewer.java:917) [java] at org.eclipse.jface.viewers.AbstractTreeViewer.getSortedChildren(AbstractTreeViewer.java:605) [java] at org.eclipse.jface.viewers.AbstractTreeViewer.updateChildren(AbstractTreeViewer.java:2620) [java] at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefreshStruct(AbstractTreeViewer.java:1908) [java] at org.eclipse.jface.viewers.TreeViewer.internalRefreshStruct(TreeViewer.java:721) [java] at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefreshStruct(AbstractTreeViewer.java:1915) [java] at org.eclipse.jface.viewers.TreeViewer.internalRefreshStruct(TreeViewer.java:721) [java] at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefresh(AbstractTreeViewer.java:1883) [java] at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefresh(AbstractTreeViewer.java:1840) [java] at org.eclipse.ui.navigator.CommonViewer.internalRefresh(CommonViewer.java:561) [java] at org.eclipse.jface.viewers.StructuredViewer$8.run(StructuredViewer.java:1535) [java] at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1443) [java] at org.eclipse.jface.viewers.TreeViewer.preservingSelection(TreeViewer.java:403) [java] at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1404) [java] at org.eclipse.jface.viewers.StructuredViewer.refresh(StructuredViewer.java:1533) [java] at org.eclipse.jface.viewers.ColumnViewer.refresh(ColumnViewer.java:548) [java] at org.eclipse.ui.navigator.CommonViewer.refresh(CommonViewer.java:353) [java] at org.eclipse.ui.navigator.CommonViewer.refresh(CommonViewer.java:510) [java] at org.eclipse.jface.viewers.StructuredViewer.refresh(StructuredViewer.java:1465) [java] at org.jboss.tools.seam.ui.views.AbstractSeamContentProvider$3.run(AbstractSeamContentProvider.java:224) [java] at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35) [java] at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:135) [java] at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3563) [java] at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3212) [java] at org.eclipse.jface.operation.ModalContext$ModalContextThread.block(ModalContext.java:173) [java] at org.eclipse.jface.operation.ModalContext.run(ModalContext.java:388) [java] at org.eclipse.ltk.internal.ui.refactoring.RefactoringWizardDialog2.run(RefactoringWizardDialog2.java:331) [java] at org.eclipse.ltk.ui.refactoring.RefactoringWizard.internalPerformFinish(RefactoringWizard.java:605) [java] at org.eclipse.ltk.ui.refactoring.UserInputWizardPage.performFinish(UserInputWizardPage.java:153) [java] at org.eclipse.ltk.ui.refactoring.resource.DeleteResourcesWizard$DeleteResourcesRefactoringConfigurationPage.performFinish(DeleteResourcesWizard.java:151) [java] at org.eclipse.ltk.ui.refactoring.RefactoringWizard.performFinish(RefactoringWizard.java:678) [java] at org.eclipse.ltk.internal.ui.refactoring.RefactoringWizardDialog2.okPressed(RefactoringWizardDialog2.java:455) [java] at org.eclipse.jface.dialogs.Dialog.buttonPressed(Dialog.java:472) [java] at org.eclipse.jface.dialogs.Dialog$2.widgetSelected(Dialog.java:624) [java] at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:240) [java] at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) [java] at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1258) [java] at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1282) [java] at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1267) [java] at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:1061) [java] at org.eclipse.swtbot.swt.finder.widgets.AbstractSWTBot$2.run(AbstractSWTBot.java:159) [java] at org.eclipse.swtbot.swt.finder.finders.UIThreadRunnable$5.doRun(UIThreadRunnable.java:221) [java] at org.eclipse.swtbot.swt.finder.finders.UIThreadRunnable$1.run(UIThreadRunnable.java:89) [java] at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35) [java] at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:135) [java] at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3563) [java] at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3212) [java] at org.eclipse.jface.window.Window.runEventLoop(Window.java:825) [java] at org.eclipse.jface.window.Window.open(Window.java:801) [java] at org.eclipse.ltk.ui.refactoring.RefactoringWizardOpenOperation$1.run(RefactoringWizardOpenOperation.java:181) [java] at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70) [java] at org.eclipse.ltk.ui.refactoring.RefactoringWizardOpenOperation.run(RefactoringWizardOpenOperation.java:193) [java] at org.eclipse.ltk.ui.refactoring.RefactoringWizardOpenOperation.run(RefactoringWizardOpenOperation.java:116) [java] at org.eclipse.ltk.internal.ui.refactoring.actions.DeleteResourcesHandler.execute(DeleteResourcesHandler.java:40) [java] at org.eclipse.ui.internal.handlers.HandlerProxy.execute(HandlerProxy.java:293) [java] at org.eclipse.core.commands.Command.executeWithChecks(Command.java:476) [java] at org.eclipse.core.commands.ParameterizedCommand.executeWithChecks(ParameterizedCommand.java:508) [java] at org.eclipse.ui.internal.handlers.HandlerService.executeCommandInContext(HandlerService.java:270) [java] at org.eclipse.ui.internal.ide.actions.LTKLauncher.runCommand(LTKLauncher.java:95) [java] at org.eclipse.ui.internal.ide.actions.LTKLauncher.openDeleteWizard(LTKLauncher.java:47) [java] at org.eclipse.ui.actions.DeleteResourceAction.run(DeleteResourceAction.java:474) [java] at org.eclipse.jdt.internal.ui.refactoring.reorg.DeleteAction.run(DeleteAction.java:165) [java] at org.eclipse.jdt.ui.actions.SelectionDispatchAction.dispatchRun(SelectionDispatchAction.java:275) [java] at org.eclipse.jdt.ui.actions.SelectionDispatchAction.run(SelectionDispatchAction.java:251) [java] at org.eclipse.jface.action.Action.runWithEvent(Action.java:498) [java] at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:584) [java] at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:501) [java] at org.eclipse.jface.action.ActionContributionItem$5.handleEvent(ActionContributionItem.java:411) [java] at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) [java] at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1258) [java] at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1282) [java] at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1267) [java] at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:1061) [java] at org.eclipse.swtbot.swt.finder.widgets.AbstractSWTBot$2.run(AbstractSWTBot.java:159) [java] at org.eclipse.swtbot.swt.finder.finders.UIThreadRunnable$5.doRun(UIThreadRunnable.java:221) [java] at org.eclipse.swtbot.swt.finder.finders.UIThreadRunnable$1.run(UIThreadRunnable.java:89) [java] at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35) [java] at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:135) [java] at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3563) [java] at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3212) [java] at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2696) [java] at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2660) [java] at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2494) [java] at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:674) [java] at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332) [java] at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:667) [java] at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149) [java] at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:123) [java] at org.eclipse.swtbot.eclipse.junit4.headless.UITestApplication.start(UITestApplication.java:53) [java] at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196) [java] at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110) [java] at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79) [java] at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:344) [java] at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179) [java] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [java] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) [java] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [java] at java.lang.reflect.Method.invoke(Method.java:616) [java] at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622) [java] at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577) [java] at org.eclipse.equinox.launcher.Main.run(Main.java:1410) [java] at org.eclipse.equinox.launcher.Main.main(Main.java:1386) [java] at org.eclipse.core.launcher.Main.main(Main.java:34)