Allow Java 17 as target bytecode

[chiquitinxx]

I don't know if Groovy 3.0.9 is fully or first compatible version with Java 17. I have tested with a Java project and at least Spock tests are running.

[keeganwitt]

I don't know if Groovy 3.0.9 is fully or first compatible version with Java 17. I have tested with a Java project and at least Spock tests are running.

Thank you for the PR! It looks like 3.0.8 was the first 3.x release. We also have to support when it was added on the 4.x line, which was 4.0.0-alpha-3. Also, it'd be good to update the JavaDoc (it will be used for the Maven site documentation for that parameter).

[keeganwitt]

Also be aware Groovy 3 doesn't completely support Java >= 16. I guess I missed a conversation somewhere. Paul reiterated this here.

For Groovy 3, JDK 16/17 has full support at the ASM level but only partial with respect to the illegal access errors seen in previous versions.

• If you have simple scripts, everything may work as per Groovy 4
• Sometimes you might still get warnings like in earlier JDKs
• Sometimes where you used to get warnings, the code will no longer work.
• We may backport some of the Groovy 4 changes to earlier versions, e.g. GROOVY-10137/GROOVY-10138

To give you an idea, last time I ran the test suite of approx 11000 tests around 40 are affected.
Example errors:

• groovy.lang.MissingMethodException: No signature of method: java.net.URLStreamHandler.parseURL() is applicable for argument types: (URL, String, Integer, Integer) values: [map:, map://local/, 4, 12] // call of protected method
• groovy.lang.MissingMethodException: No signature of method: Dolly.clone() // call of protected method

A GA release of Groovy 4 I think isn't far away, based on discussions.

[keeganwitt]

Since this was already like 90% of the way there, I went ahead and made the final adjustments. Thanks again for the PR!

[chiquitinxx]

Thank you for so fast release :)