public Collection<V> getPredecessors(GDirectedGraph<V, E> graph, V v) {
		if (isTopDown) {
			return asCollection(graph.getPredecessors(v));
		}
		return asCollection(graph.getSuccessors(v));
	}
Gets all parent vertices of the given vertex, depending upon the direction of the 
navigator.

@param graph the graph
@param v the vertex 
@return the vertices
Ghidra/Framework/Graph/src/main/java/ghidra/graph/algo/GraphNavigator.java