NPE by collapsing signature element tree

What steps will reproduce the problem?
1. Open a valid file with iDocIt!
2. Expand the SignatureElement tree
3. Select a SignatureElement (any sub element)
4. Collapse the sub tree with the selected SignatureElement

What is the expected output?

Nothing is selected and the recommended roles and the right composite with the 
documentations should be cleared OR the signature element that was collapsed is 
selected and the mentioned composites refreshes with the new information.

What do you see instead?

The recommended roles composite and the right composite with the documentations 
do not refresh and an NPE occurs:

java.lang.NullPointerException
    at de.akra.idocit.ui.composites.EditArtifactDocumentationComposite$1.selectionChanged(EditArtifactDocumentationComposite.java:217)
    at de.akra.idocit.ui.composites.EditArtifactDocumentationComposite$1.selectionChanged(EditArtifactDocumentationComposite.java:1)
    at org.pocui.swt.composites.AbsComposite.fireChangeEvent(AbsComposite.java:127)
    at de.akra.idocit.ui.composites.SelectSignatureElementComposite.treeSelectionChanged(SelectSignatureElementComposite.java:186)
    at de.akra.idocit.ui.composites.SelectSignatureElementComposite.access$2(SelectSignatureElementComposite.java:175)
    at de.akra.idocit.ui.composites.SelectSignatureElementComposite$1.selectionChanged(SelectSignatureElementComposite.java:127)
    at org.eclipse.jface.viewers.Viewer$2.run(Viewer.java:162)
    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.viewers.Viewer.fireSelectionChanged(Viewer.java:160)
    at org.eclipse.jface.viewers.StructuredViewer.updateSelection(StructuredViewer.java:2162)
    at org.eclipse.jface.viewers.StructuredViewer.handleSelect(StructuredViewer.java:1190)
    at org.eclipse.jface.viewers.StructuredViewer$4.widgetSelected(StructuredViewer.java:1220)
    at org.eclipse.jface.util.OpenStrategy.fireSelectionEvent(OpenStrategy.java:228)
    at org.eclipse.jface.util.OpenStrategy.access$4(OpenStrategy.java:222)
    at org.eclipse.jface.util.OpenStrategy$1.handleEvent(OpenStrategy.java:389)
    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1258)
    at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3540)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3161)
    at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2640)
    at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2604)
    at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2438)
    at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:671)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
    at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:664)
    at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
    at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:115)
    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:369)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:620)
    at org.eclipse.equinox.launcher.Main.basicRun(Main.java:575)
    at org.eclipse.equinox.launcher.Main.run(Main.java:1408)
    at org.eclipse.equinox.launcher.Main.main(Main.java:1384)
Original issue reported on code.google.com by dirk.mei...@gmail.com on 18 Oct 2011 at 2:38
0xCAB / idocit

NPE by collapsing signature element tree #70
