private void filterRedundantNodes() {

		Set<GTreeNode> nodeSet = new HashSet<>(copyMoveNodes);
		List<GTreeNode> filteredList = new ArrayList<>();

		for (GTreeNode node : nodeSet) {
			if (!containsAncestor(nodeSet, node)) {
				filteredList.add(node);
			}
		}

		copyMoveNodes = filteredList;
	}
Returns true if the given data type's source archive is the same as it's current data
type manager.  This is false if copying a new type from the program to an
external archive.

@param dt the type
@return true if the given type already lives in its source archive
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/datamgr/util/DataTypeTreeCopyMoveTask.java