Bug 218467 [Undo] Tighten up IUndoableOperation spec and AbstractOperation to discourage/prevent null labels
GMF creates CompositeCommands with null labels. These NPE when shortenText(getOperation().getLabel()) is invoked from update.
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/operations/AbstractOperation.java
Assert.isNotNull(context);
		for (int i = 0; i < contexts.size(); i++) {
			IUndoContext otherContext = (IUndoContext) contexts.get(i);
			
			
			
			if (context.matches(otherContext) || otherContext.matches(context)) {
				return true;
			}
		}
		return false;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.core.commands.operations.IUndoableOperation#redo(org.eclipse.core.runtime.IProgressMonitor,
	 *      org.eclipse.core.runtime.IAdaptable)
	 */
	public abstract IStatus redo(IProgressMonitor monitor, IAdaptable info)
			throws ExecutionException;
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.core.commands.operations.IUndoableOperation#removeContext(org.eclipse.core.commands.operations.IUndoContext)
	 *      <p> Default implementation. Subclasses may override this method.
	 *      </p>
	 */
	public void removeContext(IUndoContext context) {
		contexts.remove(context);
	}