anchor.diff:  RollBackOne
       :   . {
               // a trick to handle GStrings followed by EOF properly
  -            if (EOF == _input.LA(1) && ('"' == _input.LA(-1) || '/' == _input.LA(-1))) {
  +            int readChar = _input.LA(-1);
  +            if (EOF == _input.LA(1) && ('"' == readChar || '/' == readChar)) {
                   setType(GStringEnd);
               } else {
                   setChannel(HIDDEN);
  
positive.code:     import java.util.Collections;
      import java.util.Arrays;
      import java.util.stream.IntStream;
  }
  
  @members {
  
negative.code: }
  
  @header {
      import java.util.Deque;
      import java.util.ArrayDeque;
      import java.util.Map;
  