Bug 25845 Support for manually attaching source to a class path container
From Dejan: There is a work item on the ability to manually attach source to classpath entries managed by classpath container. We discussed it and we have workable options but we would like if we can have it by M3 because we want to start self-hosting using classpath containers ourselves.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/ClassFileEditor.java
*  // replace default action with class file specific ones
		 *
		 *	setAction(ITextEditorActionConstants.BOOKMARK, new AddClassFileMarkerAction("AddBookmark.", this, IMarker.BOOKMARK, true)); 
		 *	setAction(ITextEditorActionConstants.ADD_TASK, new AddClassFileMarkerAction("AddTask.", this, IMarker.TASK, false)); 
		 *	setAction(ITextEditorActionConstants.RULER_MANAGE_BOOKMARKS, new ClassFileMarkerRulerAction("ManageBookmarks.", getVerticalRuler(), this, IMarker.BOOKMARK, true)); 
		 *	setAction(ITextEditorActionConstants.RULER_MANAGE_TASKS, new ClassFileMarkerRulerAction("ManageTasks.", getVerticalRuler(), this, IMarker.TASK, true)); 
		 */
		setAction(ITextEditorActionConstants.BOOKMARK, null);
		setAction(ITextEditorActionConstants.ADD_TASK, null);		
	}
	
	/*
	 * @see JavaEditor#getElementAt(int)
	 */
	protected IJavaElement getElementAt(int offset) {
		if (getEditorInput() instanceof IClassFileEditorInput) {
			try {
				IClassFileEditorInput input= (IClassFileEditorInput) getEditorInput();
				return input.getClassFile().getElementAt(offset);
			} catch (JavaModelException x) {
			}
		}
		return null;
	}
	
	/*
	 * @see JavaEditor#getCorrespondingElement(IJavaElement)
	 */
	protected IJavaElement getCorrespondingElement(IJavaElement element) {
		if (getEditorInput() instanceof IClassFileEditorInput) {