In the code below, connClientId is taken from client configuration. It may be explicitly set, or it may be unset, i.e. null. I want to create ProtonJ2 client and use the client id when it was specified.

The following does not work. When connClientId is null, I get exception from ProtonJ2 that the parameter may not be null.

ClientOptions clientOptions = new ClientOptions();
if (connClientId != null) {
    clientOptions.id(connClientId);
}

Client client = Client.create(clientOptions);

Objects.requireNonNull(options.id(), "User supplied container Id must be non-null");

This is slightly inconvenient. Furthermore, it means that I am not able to set other client options (besides the id) and have ProtonJ2 generate a random ID for me. As far as I can tell, there is no recommendation for suitable method for generating random ID myself.