code: public static byte[] concat(byte[]... arrays) {
  		int size = 0;
  		for (byte[] a: arrays) {
  			size += a.length;
  		}
  		byte[] result = new byte[size];
  		int index = 0;
  		for (byte[] a: arrays) {
  			System.arraycopy(a, 0, result, index, a.length);
  			index += a.length;
  		}
  		return result;
  	}
docs: Substitute for Scala's Array.concat()