code: public String getMessage() {
          StringBuffer sb = new StringBuffer();
          sb.append(getReason());
          if (index > -1) {
              sb.append(" at index ");
              sb.append(index);
          }
          sb.append(": ");
          sb.append(input);
          return sb.toString();
      }
docs: Returns a string describing the parse error.  The resulting string
  consists of the reason string followed by a colon character
  ({@code ':'}), a space, and the input string.  If the error index is
  defined then the string {@code " at index "} followed by the index, in
  decimal, is inserted after the reason string and before the colon
  character.
  
  @return  A string describing the parse error