code: public StringBuffer _generatePattern(StringBuffer result,
              boolean escapeUnprintable, boolean includeStrings) {
          return appendNewPattern(result, escapeUnprintable, includeStrings);
      }
docs: Generate and append a string representation of this set to result.
  This does not use this.pat, the cleaned up copy of the string
  passed to applyPattern().
  @param includeStrings if false, doesn't include the strings.