public Vertex goToNextWhiteChild(Vertex v) {
		if (this.hasWhiteChild(v)) {
			Iterator<Vertex> it = this.getChildren(v).iterator();
			while (it.hasNext()) {
				Vertex nextChild = it.next();
				if (this.getColor(nextChild) == white) {
					this.setCallingParent(nextChild, v);
					return nextChild;
				}
			}
		}
		return null;
	}
Goes to the next child of v that has not been visited and sets the
calling parent to be v so that we can backtrack.
Ghidra/Framework/Generic/src/main/java/ghidra/util/graph/Dominator.java