code: @Override
      protected String toUtf16Escape(final int codepoint) {
          final char[] surrogatePair = Character.toChars(codepoint);
          return "\\u" + hex(surrogatePair[0]) + "\\u" + hex(surrogatePair[1]);
      }
docs: Converts the given codepoint to a hex string of the form {@code "\\uXXXX\\uXXXX"}.
  
  @param codepoint            a Unicode code point
  @return the hex string for the given codepoint