question: public static int countAdjErrors ( Graph graph1 , Graph graph2 ) { if ( graph1 == null ) { throw new NullPointerException ( "The reference graph is missing." ) ; } if ( graph2 == null ) { throw new NullPointerException ( "The target graph is missing." ) ; } graph2 = GraphUtils . replaceNodes ( graph2 , graph1 . getNodes ( ) ) ; graph1 = GraphUtils . undirectedGraph ( graph1 ) ; graph2 = GraphUtils . undirectedGraph ( graph2 ) ; int count = 0 ; Set < Edge > edges1 = graph1 . getEdges ( ) ; for ( Edge edge : edges1 ) { if ( ! graph2 . isAdjacentTo ( edge . getNode1 ( ) , edge . getNode2 ( ) ) ) { ++ count ; } } return count ; }
target:  Counts the adjacencies that are in graph1 but not in graph2.