Bug 54900 [rulers] Java Editor does not show ruler on external Java files
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitDocumentProvider.java
return cuInfo.fCopy;
		
		return null;
	}
	/*
	 * @see org.eclipse.jdt.internal.ui.javaeditor.ICompilationUnitDocumentProvider#shutdown()
	 */
	public void shutdown() {
		JavaPlugin.getDefault().getPreferenceStore().removePropertyChangeListener(fPropertyListener);
		Iterator e= getConnectedElementsIterator();
		while (e.hasNext())
			disconnect(e.next());
		fFakeCUInfoMap.clear();
	}
	/*
	 * @see org.eclipse.jdt.internal.ui.javaeditor.ICompilationUnitDocumentProvider#saveDocumentContent(org.eclipse.core.runtime.IProgressMonitor, java.lang.Object, org.eclipse.jface.text.IDocument, boolean)
	 */
	public void saveDocumentContent(IProgressMonitor monitor, Object element, IDocument document, boolean overwrite) throws CoreException {
		if (!fIsAboutToSave)
			return;
		super.saveDocument(monitor, element, document, overwrite);
	}
	/*
	 * @see org.eclipse.jdt.internal.ui.javaeditor.ICompilationUnitDocumentProvider#createLineTracker(java.lang.Object)
	 */
	public ILineTracker createLineTracker(Object element) {
		return new DefaultLineTracker();
	}
}