I'm not sure which challenges you are referring to. In my experience the biggest challenge is understanding all of the features Spring brings to a project, and how to use them to your advantage without seeming too "magical" - you can do this much easier if you are have the complete picture of how Spring works, and are not just copy pasting things from the internet. Also make sure you have a really good reason for each library or framework you use.
The source code that comes with the book has over a dozen working example projects that demonstrate how to use each Spring project that is covered, such as Spring AOP, Spring Batch, Reactor, Spring Data JPA, Spring Mobile, and others.
You firghten me terribly. I would like to go home now. Here, take this tiny ad: