This is the worst book I've ever read:
1- 75% of the examples does not work.
2- there is no good explanation, it only mentions the subjects and give you an example (that of course does not work!)
3- It keeps talking about Gradle like it's the king of everything.
4- If you are here to get some general concepts about the build process, please RUN!
5- finally, better reading an article rather than reading this horrible terrible awful awkward book.