I was a Java apologist for a long time and I still think you can write fine software in it (and the JVM is an incredible piece of engineering). But the fact that the class is the _only_ unit of abstraction is just so frustrating to me now (Yegge's Execution in the Kingdom of Nouns makes this criticism in a humorous allegory[1]). Modern Java does mitigate this somewhat. Lambdas provide nice sugar over the inline class-creation you'd have to do of yore. Records make it less of a pain to define POJOs. But I think this fundamental issue is at the root of much of the language's clunkiness.
They were close but unfortunately went too far at being opinionated in solve the issues of using C at the time of Java's inception. Changing this now is Valhalla project which has unknown release date.
Luckily, C# learned from this mistake and made a decision to follow C much closely, having integers as proper primitives and supporting structs since day 1, and only improved since then in this area (JVM needs insane pointer compression and shadow tricks to pack integers to claw back performance, and in .NET "it just works" instead).
I wonder if Cassandra was written in .NET, it wouldn't have such a poor performance (though this can also be showcased by Garnet which beats competition written in C++ and C).
[1] http://steve-yegge.blogspot.com/2006/03/execution-in-kingdom...