@Override
  public ChaCha20Poly1305Parameters getParameters() {
    return parameters;
  }
Represents the Aead ChaCha20-Poly1305 specified in RFC 8439.

<p>ChaCha20-Poly1305 allows no parameters; hence the main part here is really just the keys.
However, Tink allows prefixing every ciphertext with an ID-dependent prefix, see {@link
ChaCha20Poly1305Parameters.Variant}.
java_src/src/main/java/com/google/crypto/tink/aead/ChaCha20Poly1305Key.java