public void add(String category, List<T> items) {
		List<T> list = dataMap.computeIfAbsent(category, c -> new ArrayList<T>());
		list.addAll(items);
		displayEntries = null;
	}
Adds the list of items to the given category. If the category already exists, these items
will be added to any items already associated with that cateogry.
@param category the category to add the items to
@param items the list of items to add to and be associated with the given category
Ghidra/Framework/Docking/src/main/java/docking/widgets/searchlist/DefaultSearchListModel.java