The book is about web app development not in the SPA style with a JSON API but the good old way of having the server rendering html responses.
Java, Spring Boot, JPA, Thymeleaf and Tailwind CSS are used for this.
While I like the "server side rendering" approach, the rest of the book is not so suitable for me.
Spring brings a lot of magic and JPA brings a lot of complexity. As a result I do not like the structure of the codebase when the book is finished.
Also I am big fan of the "no build" concept in the context of java script and npm. I don't want to have npm at in my project, so Tailwind is not the right choice for me.
For myself I have found the best way in Alex Edward's book "Let's Go". However, if you want to, or have to use Java, Spring and JPA then I can recommend this Book very well.