@Override public void contributeGraphEdge(ILogicalOperator src, int srcOutputIndex, ILogicalOperator dest, int destInputIndex) { ArrayList<ILogicalOperator> outputs = outEdges.get(src); if (outputs == null) { outputs = new ArrayList<>(); outEdges.put(src, outputs); } addAtPos(outputs, dest, srcOutputIndex); ArrayList<ILogicalOperator> inp = inEdges.get(dest); if (inp == null) { inp = new ArrayList<>(); inEdges.put(dest, inp); } addAtPos(inp, src, destInputIndex); }