I'm more than a little late writing my last roundup for 2014 but it includes an awesome Spring Boot book and an extremely comprehensive book about iText.
As I'm developing more and more in Spring Boot, this book has been absolutely indespensible to me. It's very well written and examples are very practical and well explained. I especially liked how code is introduced with detailed explanation of the important lines.
While most of the book is written using Java, Groovy gets some love in the first chapter and it made for a very pleasant introduction. I really enjoyed this book and I've referred back to it often since finishing it.
This book does an outstanding job of demystifying Spring Boot and all the magic that goes along with it. I very highly recommend it.
This book is incredibly comprehensive, filled with tons of examples. After reading it, I was surprised at exactly how low level the pdf format is and how much the iText library does to create a really nice abstraction over that. The later chapters really dig into the more advanced aspects of creating pdfs.
I started reading this book after I began working on my Groovy Document Builder and the lessons learned from it have been really invaluable.
While I'm transitioning away from iText for that particular project, I think this book is definitely worth a look if you're working with iText or simply want more insight about the pdf format.