No "configureUserId" method

As the title said, I found the [FAQ](https://gameanalytics.com/docs/s/article/A-B-Testing-Experiment-Set-Up-FAQs#verify-experiments) says there is a method can reset the user id in GA. But the function is not implemented in the SDK. So can anyone to implement this? Or tell me how to do this correctly, maybe I can create a pull request if I done it. Thanks!