public boolean add(@Nonnull String key, @Nonnull MenuItem item) {
		if (source.allow(key)) {
			target.add(item);
			return true;
		}
		return false;
	}
@param key
		ID of the item to add. Doubles as {@link Lang#get(String)} key.
@param item
		Menu item to add.

@return {@code true} when added. {@code false} when denied by the {@link #source()}.
recaf-ui/src/main/java/software/coley/recaf/ui/contextmenu/ItemSink.java