#vulnerable code 
                              @Override
  public void enterScope(NodeTraversal t) {
    Scope scope = t.getScope();

    // Computes the control flow graph.
    ControlFlowAnalysis cfa = new ControlFlowAnalysis(compiler, false, false);
    cfa.process(null, scope.getRootNode());
    cfgStack.push(curCfg);
    curCfg = cfa.getCfg();

    new GraphReachability<Node, ControlFlowGraph.Branch>(curCfg)
        .compute(curCfg.getEntry().getValue());
  } 
                            #location 7 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              @Override
  public void enterScope(NodeTraversal t) {}