@Override
		public void archiveOpened(Archive archive) {
			if (!isLoaded()) {
				return;
			}

			GTreeNode node = createArchiveNode(archive, dtFilterState);
			if (node == null) {
				return;
			}

			List<GTreeNode> allChildrenList = getChildren();
			int index = Collections.binarySearch(allChildrenList, node);
			if (index < 0) {
				index = -index - 1;
			}
			addNode(index, node);
		}
This implementation returns null, since this class is the root of the hierarchy and does
not have an archive.
@see ghidra.app.plugin.core.datamgr.tree.DataTypeTreeNode#getArchiveNode()
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/datamgr/tree/ArchiveRootNode.java