docs: protected Resource getXtextResource() {
  		//FIXME: for helping to resolve #661
  		final XtextEditor editor = getEditor();
  		if (editor != null) {
  			final IResource resource = editor.getResource();
  			if (resource instanceof IStorage) {
  				final IProject project = resource.getProject();
  				if (project != null) {
  					final ResourceSet resourceSet = this.resourceSetProvider.get(project);
  					assert resourceSet != null;
  					final URI uri = this.uriMapper.getUri((IStorage) resource);
  					return resourceSet.getResource(uri, true);
  				}
  			}
  		}
  		return null;
  	}