@Override
  public boolean hasIdRequirement() {
    return variant != Variant.NO_PREFIX;
  }
Describes how the prefix is computed. There are two main possibilities: NO_PREFIX (empty
prefix) and TINK (prefix the ciphertext with 0x01 followed by a 4-byte key id in big endian).
java_src/src/main/java/com/google/crypto/tink/aead/LegacyKmsAeadParameters.java