code: public static String fromHex(String string, int minLength, Pattern separator) {
          StringBuilder buffer = new StringBuilder();
          String[] parts = separator.split(string);
          for (String part : parts) {
              if (part.length() < minLength) {
                  throw new IllegalArgumentException("code point too short: " + part);
              }
              int cp = Integer.parseInt(part, 16);
              buffer.appendCodePoint(cp);
          }
          return buffer.toString();
      }
docs: Parse a list of hex numbers and return a string
  @param string String of hex numbers.
  @param minLength Minimal length.
  @param separator Separator.
  @return A string from hex numbers.