This book looks pretty useful.
Are most of you recipes examples of things that are already documented/somewhat documented or does your book go into solutions that are not well documented or do you cover both?
Do you have an example in the book of a solution to a problem that is likely to come up but is not commonly documented ?
The book started out as a way for me to remember solutions I'd collected from various sources on the web, like how to convert a java.util.Date into a java.time.ZonedDateTime, or how to use boxed streams (and why I needed them in the first place), or what the supplier, accumulator, and combiner arguments to the collect method meant, and so on. I kept adding items on how to use flatMap, or how to use downstream collectors, or how to change the default pool size on the common ForkJoinPool. Eventually I went back and added the basics as well, but that's not the order in which the recipes were written.
A year earlier I'd written the O'Reilly book "Gradle Recipes for Android", so I thought writing another recipes book for the same publisher would be easy. Sigh. Live and learn, I guess.
(Btw, if you go to gradle.org and register, you can download a pdf of Gradle Recipes for Android for free. It's also available on Safari, of course.