Bug 11748 switch to new DecoratorManager API
From the workbench change notes: API changes IWorkbenchPartSite.getDecoratorManager() - As the DecoratorManager has proven to be required for more than just IWorkbenchPartSites we have moved getDecoratorManager() to IWorkbench and deprecated the getDecoratorManager() in IWorkbenchPartSite. The one in IWorkbenchPartSite will be removed after the other Eclipse components have had a chance to switch to the new API.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/browsing/JavaBrowsingPart.java
/**
	 * Answers if the given <code>element</code> is a valid
	 * input for this part.
	 * 
	 * @param 	element	the object to test
	 * @return	<true> if the given element is a valid input
	 */
	abstract protected boolean isValidInput(Object element);
	/**
	 * Answers if the given <code>element</code> is a valid
	 * element for this part.
	 * 
	 * @param 	element	the object to test
	 * @return	<true> if the given element is a valid element
	 */
	protected boolean isValidElement(Object element) {
		if (element == null)
			return false;
		element= getSuitableJavaElement(element);
		if (element == null)
			return false;
		Object input= getViewer().getInput();
		if (input == null)
			return false;
		if (input instanceof Collection)
			return ((Collection)input).contains(element);
		else
			return input.equals(element);
	}
	private boolean isInputResetBy(Object newInput, Object input, IWorkbenchPart part) {