public Vertex[] getVerticesHavingReferent(Object o) {
		int cnt = 0;
		if (o == null) {
			return new Vertex[0];
		}
		Vertex[] temp = new Vertex[this.numVertices()];
		GraphIterator<Vertex> iter = this.vertexIterator();
		while (iter.hasNext()) {
			Vertex v = iter.next();
			if (v.referent() != null && v.referent().equals(o)) {
				temp[cnt++] = v;
			}
		}
		Vertex[] ans = new Vertex[cnt];
		System.arraycopy(temp, 0, ans, 0, cnt);
		return ans;
	}
Returns Vertex[] containing all vertices having the given object as
 a referent. Any number of vertices in the graph may refer back to 
the same object.
Ghidra/Framework/Generic/src/main/java/ghidra/util/graph/DirectedGraph.java