code: public static String fromByteArray(byte[] ba) {
          if ((ba != null) && (ba.length == 16)) {
              StringBuilder result = new StringBuilder(36);
              for (int i = 0; i < 16; ++i) {
                  if ((i == 4) || (i == 6) || (i == 8) || (i == 10)) {
                      result.append('-');
                  }
                  result.append(hexChars.charAt(((ba[i] & 0xF0) >>> 4)));
                  result.append(hexChars.charAt((ba[i] & 0xF)));
              }
              return result.toString();
          }
          return null;
      }
docs: Returns a uuid / guid for a given byte array.
  
  @param ba
  array of bytes containing the id
  @return id