static String getKeyType() {
    return "type.googleapis.com/google.crypto.tink.XChaCha20Poly1305Key";
  }
This instance of {@code KeyManager} generates new {@code XChaCha20Poly1305} keys and produces new
instances of {@code XChaCha20Poly1305}.
java_src/src/main/java/com/google/crypto/tink/aead/XChaCha20Poly1305KeyManager.java