Bug 319011 NPE when closing editor after closing a perspective
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/ModelServiceImpl.java
* 
	 * @see
	 * org.eclipse.e4.ui.workbench.modeling.EModelService#getAllElements(org.eclipse.e4.ui.model.
	 * application.MUIElement, java.lang.String, java.lang.Class, java.util.List)
	 */
	public <T> List<T> findElements(MUIElement searchRoot, String id, Class<T> clazz,
			List<String> tagsToMatch) {
		List<T> elements = new ArrayList<T>();
		findElementsRecursive(searchRoot, id, clazz, tagsToMatch, elements);
		return elements;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.e4.ui.workbench.modeling.EModelService#find(java.lang.String,
	 * org.eclipse.e4.ui.model.application.MElementContainer)
	 */
	public MUIElement find(String id, MUIElement searchRoot) {
		if (id == null || id.length() == 0)
			return null;
		List elements = findElements(searchRoot, id, null, null);
		if (elements.size() > 0)
			return (MUIElement) elements.get(0);
		return null;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.e4.ui.workbench.modeling.EModelService#getContainingContext(org.eclipse.e4.ui