I just disagree. This is not idiomatic Java; it's idiomatic JPA. All of the Java I see professionally and in the community uses immutable classes when not dealing with JPA entities.
I guess you live in a more modern workspace than I do. I just picked an open source project that (A) I know we use at work, and (B) I know is written in Java. I picked a random source file that sounded like it would have some mutable state, and the very first functions below the constructor were a trivial getter and setter around a private ivar.
I'm a little surprised it was in literally the first place I looked, but I'm not surprised that it was easy to find. "Use private ivars and write getters and setters to encapsulate your state" was probably the second thing that a generation of CompSci students learned in their first programming class, right after "an object is an instance of a class."
You picked a project that (A) is literally older than the sun, (B) targets Java 11, a version from 5 years ago, and (C) the file is generated.
Right at the top of the file...
> /* QueryParser.java /
/ Generated By:JavaCC: Do not edit this line. QueryParser.java */
I'm not claiming you're not going to see properties written out. I'm just saying that's not the majority of code you're going to see and to claim that idiomatic Java is all getters and setters is a bit far fetched.
Here is what I would consider modern idiomatic Java, immutable records and immutable classes that may expose some of their state:
