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
* 
	 * @param 	je 	the Java element for which to search the closest input
	 * @return	the closest Java element used as input for this part
	 */
	protected IJavaElement findInputForJavaElement(IJavaElement je) {
		if (je == null)
			return null;
		if (isValidInput(je))
			return je;
		return findInputForJavaElement(je.getParent());
	}
	
	final protected IJavaElement findElementToSelect(Object obj) {
		if (obj instanceof IJavaElement)
			return findElementToSelect((IJavaElement)obj);
		return null;
	}
	
	/**
	 * Finds the element which has to be selected in this part.
	 * 
	 * @param je	the Java element which has the focus
	 */
	abstract protected IJavaElement findElementToSelect(IJavaElement je);
	
	private Object getElementFromSingleSelection(ISelection selection) {
		if (selection instanceof StructuredSelection
			&& ((StructuredSelection)selection).size() == 1)
				return ((StructuredSelection)selection).getFirstElement();
		return null;