Any concerns updating j2objc build to Java 17 minimum?

[Tom Ball]

The j2objc team would like to update the j2objc build to require Java 17. Java 17 was released in 2021, and is a required minimum for the Android Gradle Plugin 8.0.

The main benefit of Java 17 for the j2objc build is to test support for new Java language features like switch expressions without reflection. It also will make translator tests easier to read and maintain, since most of them transpile multi-line Java snippets and match Objective-C snippets. It will also enable better error checking by javac and errorprone.

We'll likely upgrade next week, unless we hear from anyone with objections.