private Collection<GraphNode> buildSingleSet(GraphNode inputNode){
  Collection<GraphNode> input=Sets.newHashSet();
  input.add(inputNode);
  return input;
}

private Collection < GraphNode > buildSingleSet ( GraphNode inputNode ) { Collection < GraphNode > input = Sets . newHashSet ( ) ; input . add ( inputNode ) ; return input ; }
creates a new input set including the given node .
