Adding Seam 2 Settings error - eclipse

Question

I am using Eclipse Indigo, with the latest JBoss tools.
For an existing Seam 2 project I am unable to apply Seam 2 Settings to any of the Seam projects (the main seam project, ejb).
Any time that I try and set seam settings to a known Seam runtime I get the following nullpointer:
java.lang.NullPointerException
at org.eclipse.core.internal.resources.ProjectDescription.setBuildSpec(ProjectDescription.java:569)
at org.jboss.tools.jst.web.WebModelPlugin.addNatureToProjectWithValidationSupport(WebModelPlugin.java:206)
at org.jboss.tools.seam.core.SeamUtil.enableSeamSupport(SeamUtil.java:57)
at org.jboss.tools.seam.ui.preferences.SeamSettingsPreferencePage.performOk(SeamSettingsPreferencePage.java:759)
at org.eclipse.jface.preference.PreferenceDialog$13.run(PreferenceDialog.java:964)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:49)
at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:175)
at org.eclipse.jface.preference.PreferenceDialog.okPressed(PreferenceDialog.java:944)
at org.eclipse.ui.internal.dialogs.FilteredPreferenceDialog.okPressed(FilteredPreferenceDialog.java:447)
at org.eclipse.jface.preference.PreferenceDialog.buttonPressed(PreferenceDialog.java:233)
at org.eclipse.jface.dialogs.Dialog$2.widgetSelected(Dialog.java:624)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:240)
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:4165)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3754)
at org.eclipse.jface.window.Window.runEventLoop(Window.java:825)
at org.eclipse.jface.window.Window.open(Window.java:801)
at org.eclipse.ui.dialogs.PropertyDialogAction.run(PropertyDialogAction.java:158)
at org.eclipse.jface.action.Action.runWithEvent(Action.java:498)
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:4165)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3754)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2696)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2660)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2494)
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:674)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:667)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:123)
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:344)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)

Answer 1

I solved this, but I never got to the root cause.
I used a version I knew worked and copied the .classpath and .project files for eclipse into the offending project. Not the best solution, but it worked. Nothing I could to manually worked in preferences when comparing the 2 projects, as they were exactly the same(except for the code base changes).

Answer 2

For me, I was able to fix this adding the buildSpec and nature tags to the .project file, then restarting eclipse.
<buildCommand>
<name>org.jboss.tools.seam.core.seambuilder</name>
<arguments>
</arguments>
</buildCommand>
...
<natures>
<nature>org.jboss.tools.seam.core.seamnature</nature>
</natures>