I've just read the (free) OpenJDK Migration for Dummies book. It was well worth my time!
I first started using Java in 1998, so I've got a long history with it and feel very comfortable with the language itself. However, the licensing changes and proliferation of OpenJDK distributions are much more recent, and those aspects can be a bit confusing.
The book is obviously written by a vendor, but it's very honest about that. It does a good job of establishing the motivation for using OpenJDK, providing actionable steps for how to pursue that migration, and presenting meaningful information that a business should consider when selecting an OpenJDK vendor.
There were also quite a few things that might not have crossed my mind, such as support for NTLM authentication or the availability of the Lucida fonts.
The only errors I spotted were for the URLs in the book. There were several places (mostly near the front) where the .com was omitted from openjdk-migration.com and once where the .com was .con instead.
Also, as someone who used Java on Linux in the late 1990s, I think the History section should have at least mentioned Blackdown Java (which is kind of the primordial OpenJDK IMHO), because some of us remember volunteers stepped up to deliver Java on Linux when Sun ignored that platform.
Thanks again for writing this book, Simon Ritter! I really enjoyed it.