private void adjustDepth(Depth parentDepth) {
			depth = Math.max(depth, parentDepth.depth + 1);
		}
Sorts the vertices in this graph topologically.

@param root the start node for traversing the graph (will always be the first node in the
resulting list)
@return a list of vertices reachable from the given root vertex, sorted topologically
Ghidra/Framework/Graph/src/main/java/ghidra/graph/GraphToTreeAlgorithm.java