docs: public static byte[] convertUtf16UnitsToUtf8(String text)
      {
          byte[] data = new byte[4*text.length()];
          int limit = 0;
          for (int i = 0; i < text.length(); i++)
          {
              char c = text.charAt(i);
              limit += IonUTF8.convertToUTF8Bytes(c, data, limit,
                                                  data.length - limit);
          }
  
          byte[] result = new byte[limit];
          System.arraycopy(data, 0, result, 0, limit);
          return result;
      }