Bug 12585 Packages view should not provide file and resource transfer if Java element below CU is selected
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/dnd/DelegatingDragAdapter.java
fFinishListener= null;
		boolean saveDoit= event.doit;
		Object saveData= event.data;
		boolean doIt= false;
		List transfers= new ArrayList(fPossibleListeners.length);
		fActiveListeners= new ArrayList(fPossibleListeners.length);
		
		for (int i= 0; i < fPossibleListeners.length; i++) {
			TransferDragSourceListener listener= fPossibleListeners[i];
			event.doit= saveDoit;
			listener.dragStart(event);
			if (event.doit) {
				transfers.add(listener.getTransfer());
				fActiveListeners.add(listener);
			}
			doIt= doIt || event.doit;
		}
		if (doIt) {
			((DragSource)event.widget).setTransfer((Transfer[])transfers.toArray(new Transfer[transfers.size()]));
		}
		event.data= saveData;
		event.doit= doIt;
	}
	/* non Java-doc
	 * @see DragSourceListener
	 */
	public void dragSetData(DragSourceEvent event) {
		fFinishListener= getListener(event.dataType);
		if (fFinishListener != null)
			fFinishListener.dragSetData(event);