message: Fixed bug found by test where the ciphertext was not the same for null and empty aad even though the decryption worked
diff: @@ -76,10 +76,13 @@ public final class AesSiv implements DeterministicAead {
  byte[] result = cmacForS2V.computeMac(BLOCK_ZERO);
  for (int i = 0; i < s.length - 1; i++) {
  - byte[] currBlock = s[i];
  - if (currBlock != null) {
  - result = Bytes.xor(AesUtil.dbl(result), cmacForS2V.computeMac(currBlock));
  + final byte[] currBlock;
  + if (s[i] == null) {
  + currBlock = new byte[0];
  + } else {
  + currBlock = s[i];
  }
  + result = Bytes.xor(AesUtil.dbl(result), cmacForS2V.computeMac(currBlock));
  }
  byte[] lastBlock = s[s.length - 1];
  if (lastBlock.length >= 16) {
  