@Override
	public GTreeFilter getFilter() {
		GTreeFilter filter = super.getFilter();
		if (filter == null) {
			return secondaryFilter;
		}
		return new CombinedGTreeFilter(filter, secondaryFilter);
	}
A filter that allows for an additional second filter.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/datamgr/actions/SecondaryTreeFilterProvider.java