docs: public static String unicodeToUtf8(String theString) {
          if (theString == null) {
              return null;
          }
          char aChar;
          int len = theString.length();
          StringBuffer outBuffer = new StringBuffer(len);
          for (int x = 0; x < len; ) {
              aChar = theString.charAt(x++);
              if (aChar == '\\') {
                  aChar = theString.charAt(x++);
                  if (aChar == 'u') {
                      // Read the xxxx
                      int value = 0;
                      for (int i = 0; i < 4; i++) {
                          aChar = theString.charAt(x++);
                          switch (aChar) {
                              case '0':
                              case '1':
                              case '2':
                              case '3':
                              case '4':
                              case '5':
                              case '6':
                              case '7':
                              case '8':
                              case '9':
                                  value = (value << 4) + aChar - '0';
                                  break;
                              case 'a':
                              case 'b':
                              case 'c':
                              case 'd':
                              case 'e':
                              case 'f':
                                  value = (value << 4) + 10 + aChar - 'a';
                                  break;
                              case 'A':
                              case 'B':
                              case 'C':
                              case 'D':
                              case 'E':
                              case 'F':
                                  value = (value << 4) + 10 + aChar - 'A';
                                  break;
                              default:
                                  //throw new IllegalArgumentException("Malformed   \\uxxxx   encoding." + value);
                                  // filter this bad case
                                  value = 0;
                                  break;
                          }
                      }
                      outBuffer.append((char) value);
                  } else {
                      if (aChar == 't') {
                          aChar = '\t';
                      } else if (aChar == 'r') {
                          aChar = '\r';
                      } else if (aChar == 'n') {
                          aChar = '\n';
                      } else if (aChar == 'f') {
                          aChar = '\f';
                      }
                      outBuffer.append(aChar);
                  }
              } else {
                  outBuffer.append(aChar);
              }
          }
          return outBuffer.toString();
      }