public void add(T t) {

		if (isBroadcasting) {
			return;
		}

		if (ignoreItem(t)) {
			return;
		}

		dropNull();

		// once we add a new item, any old history that was after this item needs to be
		// removed, as that is old alternate timeline that no longer makes sense
		trimHistoryToCurrentIndex();

		handleDuplicate(t);

		historyStack.push(t);

		// '- 1' because we want to be at the new item
		historyIndex = historyStack.size() - 1;
	}
Adds an item to this history list.  <code>null</code> values are ignored.

<p>Calls to this method during selection notification will have no effect.  If you need
to update the history during a notification, then you must do so at a later time, perhaps
by using  {@link SystemUtilities#runSwingLater(Runnable)}.

@param t the item to add.
Ghidra/Framework/Generic/src/main/java/util/HistoryList.java