Congratulations on your book! I'm sure it will be a great success.
One question that came to mind about this book is, "How is this one different from all the other Spring Framework books out there?" Why should I consider your book over an Oreilly or a Manning book, or even a Udemy course?
The books are different in how the authors present the topics. I find that Getting started with Spring Framework books goes into the depth and width of the Spring Framework, and provides numerous simple examples (close to 88 sample projects) to get you started with Spring Framework. It is also the first book currently that discusses function/reactive programming support in Spring 5.