Bug 88577 [Viewers] Deferred viewers in JFace have a dependency on Job
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/deferred/BackgroundContentProvider.java
private void cancelSortJob() {
        sortMon.cancel();
        sortJob.cancel();
    }
    
    /**
     * Called when new elements are added to the model.
     * 
     * @param toAdd newly added elements
     */
    private void add(Object[] toAdd) {
    	changeQueue.enqueue(ChangeQueue.ADD, toAdd);
    	makeDirty();
    }
    
    /**
     * Called with the complete contents of the model
     * 
     * @param contents new contents of the model
     */
    private void setContents(Object[] contents) {
    	changeQueue.enqueue(ChangeQueue.SET, contents);
    	makeDirty();
    }
    /**
     * Called when elements are removed from the model
     * 
     * @param toRemove elements removed from the model
     */
    private void remove(Object[] toRemove) {