I don't have a dedicated section on debugging, since that's usually dependent on whatever
IDE you're using. I do, however, talk about the peek method, which is a great way to monitor stream values as they are processed in a stream pipeline. The peek method takes each value and returns it. You provide a Consumer argument (so you don't change what's being returned) that allows you to log the value, or do whatever else you want to do. I find that peek method very useful.
That said, IntelliJ IDEA has an awesome stream debugger plugin that you might want to try.