private static com.google.crypto.tink.proto.Ed25519PublicKey getProtoPublicKey(
      Ed25519PublicKey key) {
    return com.google.crypto.tink.proto.Ed25519PublicKey.newBuilder()
        .setKeyValue(ByteString.copyFrom(key.getPublicKeyBytes().toByteArray()))
        .build();
  }
Registers previously defined parser/serializer objects into a given registry.
java_src/src/main/java/com/google/crypto/tink/signature/internal/Ed25519ProtoSerialization.java