Review

class VariableReferenceCheck.ReferenceCheckingBehavior {
    @Override
    public void afterExitScope(NodeTraversal t,
        Map<Var, ReferenceCollection> referenceMap) {

      // Check all vars after finishing a scope
      for (Iterator<Var> it = t.getScope().getVars(); it.hasNext();) {
        Var v = it.next();
        checkVar(t, v, referenceMap.get(v).references);
      }
    }

}