Vert.x provides the things like databases, redis, too. And no I don't use Vert.x However in Java it isn't that hard anymore to make a Sync Library Async, especially JDBC. Thanks to CompletableFuture on Java8, the problem is, is that not lot's of companies are on Java8, however if you are using vert.x that shouldn't be the case.

Libraries in Java are mostly Synchronous cause people use Java4, Java5, Java6, Java7 and not Lambda's and Futures. I mean there are really libraries out there who providing Java4 support. They provided Java3 Support until the end of 2014.. Especially Libraries who are generating content are having backwards compability to the beginnings.

Edit: Oh and the Vert.x JDBC Client is a wrapper around JDBC with RxJava / Future's. Which is basically the best thing you could do. Edit2: Oh and what I dislike more than synchronous code is code that has getters and setters, since that makes it hard to wrap a library into a thread pool since mutable data isn't a nice thing to deal with inside a async fashion. However it was traditional to have getter and setter classes . But more and more this isn't the case for newer things.