private static byte[] generateMultipartBoundary(){
  final Random rand=new Random();
  final byte[] bytes=new byte[rand.nextInt(11) + 30];
  for (int i=0; i < bytes.length; i++) {
    bytes[i]=MULTIPART_CHARS[rand.nextInt(MULTIPART_CHARS.length)];
  }
  return bytes;
}

private static byte [ ] generateMultipartBoundary ( ) { final Random rand = new Random ( ) ; final byte [ ] bytes = new byte [ rand . nextInt ( 11 ) + 30 ] ; for ( int i = 0 ; i < bytes . length ; i ++ ) { bytes [ i ] = MULTIPART_CHARS [ rand . nextInt ( MULTIPART_CHARS . length ) ] ; } return bytes ; }
generates a random multipart boundary string .
