code: @Override
    public ParseSetup createParserSetup(Key[] inputs, ParseSetup requiredSetup) {
  
      FileVec f;
      Object frameOrVec = DKV.getGet(inputs[0]);
  
      if (frameOrVec instanceof water.fvec.Frame)
        f = (FileVec) ((Frame) frameOrVec).vec(0);
      else
        f = (FileVec) frameOrVec;
      return readSetup(f, requiredSetup.getColumnNames(), requiredSetup.getColumnTypes());
    }
docs: Use only the first file to setup everything.
  
  @param inputs  input keys
  @param requiredSetup  user given parser setup
  @return