public CategoryNode findCategoryNode(Category category) {
		for (GTreeNode node : getChildren()) {
			ArchiveNode archiveNode = (ArchiveNode) node;
			CategoryNode categoryNode = archiveNode.findCategoryNode(category);
			if (categoryNode != null) {
				return categoryNode;
			}
		}
		return null;
	}
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