Bug 287103 [CommonNavigator] contentServiceLabelProvider doesn't properly implement overrides
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/ContributorTrackingSet.java
* 
	 * @param aContentService
	 * @param elements
	 */
	public ContributorTrackingSet(NavigatorContentService aContentService, Object[] elements) {
		
		for (int i = 0; i < elements.length; i++) 
			super.add(elements[i]); 
		
		contentService = aContentService;
	}
	
	/* (non-Javadoc)
	 * @see java.util.HashSet#add(java.lang.Object)
	 */
	public boolean add(Object o) { 
		if(contributor != null)
			contentService.rememberContribution(contributor, o);
		return super.add(o);
	}
	
	/* (non-Javadoc)
	 * @see java.util.HashSet#remove(java.lang.Object)
	 */
	public boolean remove(Object o) { 
		contentService.forgetContribution(o);
		return super.remove(o);
	}
	/**
	 *