Let me share my post with a detailed step by step guide how an exisiting Spark scala library may be adopted to work with recently introduced Spark Connect. As an example I have chosen a pupular open source data quality tool AWS Deequ. I made all the necessary protobuf messages and a Spark Connect Plugin. I tested it from PySpark Connect 3.5.1 and it works. Of course, all the code is public in git.