private static void validateParameters(AesCmacParameters parameters)
      throws GeneralSecurityException {
    if (parameters.getKeySizeBytes() != KEY_SIZE_IN_BYTES) {
      throw new GeneralSecurityException("AesCmacKey size wrong, must be 32 bytes");
    }
  }
This key manager generates new {@code AesCmacKey} keys and produces new instances of {@code
AesCmac}.
java_src/src/main/java/com/google/crypto/tink/mac/AesCmacKeyManager.java