@Override
  public boolean equals(Object o) {
    if (!(o instanceof LegacyKmsAeadParameters)) {
      return false;
    }
    LegacyKmsAeadParameters that = (LegacyKmsAeadParameters) o;
    return that.keyUri.equals(keyUri) && that.variant.equals(variant);
  }
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