static String getKeyType() {
    return "type.googleapis.com/google.crypto.tink.Ed25519PrivateKey";
  }
This instance of {@code KeyManager} generates new {@code Ed25519PrivateKey} keys and produces new
instances of {@code Ed25519Sign}.
java_src/src/main/java/com/google/crypto/tink/signature/Ed25519PrivateKeyManager.java