Support Java 9+ Language Features

[paulirwin]

Would like to have unit tests for all. Only tracking non-preview features for now; please file separate issues for preview features for consideration. This issue might get broken out into several.

Java 9:

• More concise try-with-resources
• Diamond syntax and Anonymous inner classes
• Underscore not legal name
• Private interface methods

Java 10:

• Local variable type inference

Java 11:

• Type inference for lambda parameters

Java 12:

(no non-preview features)

Java 13:

(no non-preview features)

Java 14:

• Switch expressions Moved to Java 14 Switch Expressions Support #63

Java 15:

• Text blocks Moved to Java 15 Text Block Support #64

Java 16:

• Record classes Moved to Java 16 Record Classes #65

Java 17:

• Sealed classes Moved to Java 17 Sealed Classes #66

Java 18:

(no non-preview features)

Java 19:

(no non-preview features)

Java 20:

(no non-preview features)

Java 21:

• Record patterns Moved to Java 21 Record Patterns #67
• Pattern matching for switch Moved to Java 21 Switch Pattern Matching #68

[paulirwin]

Java 9 support should be complete, and then I should be able to get through Java 11 (and thus Java 13) pretty quickly. Switch expressions might be a little more involved.

[paulirwin]

Java 10 and 11 type inference was already implicitly/accidentally supported, but added tests for those. We can now say that, bugs notwithstanding, we should have support for converting up to Java 13 code, including Java 11 LTS. I will break the other features out as separate standalone issues since they are larger.

[paulirwin]

Separate issues created for Java 14-21 features.