public Set<V> getDominators(V a) {
		Set<V> dominators = new HashSet<>();
		dominators.add(a);

		while (!root.equals(a)) {
			a = dominatorMap.get(a); // immediate dominator
			add(a, dominators);
		}
		return dominators;
	}
Returns all nodes that dominate the given vertex.  A node 'a' dominates node 'b' if 
all paths from start to 'b' contain 'a'.  

@param a the vertex
@return the dominating vertices
Ghidra/Framework/Graph/src/main/java/ghidra/graph/algo/ChkDominanceAlgorithm.java