Make the build work under more JDK versions.

[copybara-service]

Make the build work under more JDK versions.

(Guava is already usable under plenty of verions. This change affects only people who build it themselves.)

And run CI under JDK17. Maybe this will make CI painfully slow, but we'll see what happens. If we want to drop something, we should consider whether to revert 17 or to drop 11 instead (so as to maintain coverage at the endpoints of [8, 17]).

Notes on some of the versions

JDK9

I expected Error Prone to work, but I saw invalid flag: -Xep:NullArgumentForNonNullParameter:OFF, even though that flag is already part of the same <arg>, which works fine for other JDK versions. So I disabled Error Prone for that version.

Then I had a Javadoc problem with the --no-module-directories configuration from cl/413934851 (the fix for #5457). After reading JDK-8215582 more carefully, I get the impression that that flag might not have been added until 11: "addressed in JDK 11, along with an option to revert to the old layout in case of need." So I disabled it for 9-10.

Then I ran into a problem similar to bazelbuild/bazel#6173 / JDK-8184940. I'm not sure exactly what tool produced a file with a month of 0, but it happened only when building guava-tests. At that point, I gave up, though I left the 2 above workarounds in place.

JDK10

This fails with some kind of problem finding a Guice dependency inside Maven. I didn't investigate.

JDK15 and JDK16

These fail with the TreeMap bug that our collection testers had detected but we never got around to reporting. Thankfully, it got reported and fixed for JDK17. We could consider suppressing the tests under that version.

JDK18, JDK19, and JDK20-early-access

These fail with SecurityManager trouble.

Notes on the other actual changes

maven-javadoc-plugin

I set up maven-javadoc-plugin to use -source ${java.specification.version}. Otherwise, it would take the version from maven-compiler-plugin. That's typically fine: Guava's source code targets Java 8, so -source 8 "ought" to work. But it doesn't actually work because we also pass Javadoc the JDK sources (so that {@inheritDoc} works better), which naturally can target whichever version of the JDK we're building with.

Error Prone

While Error Prone is mostly usable on JDK11+, some of its checks have problems under some versions, at least when they're reporting warnings.

This stems from its use of part of the Checker Framework, which doesn't support JDKs in the gap between 11 and 17. And specifically, it looks like the Checker Framework is trying to look up BindingPatternTree under any JDK12+. But BindingPatternTree (besides not being present at all until JDK14) didn't declare that method until JDK16.

Anyway, the problem we saw was a NoSuchMethodException during the AbstractReferenceEquality call to NullnessAnalysis.getNullness, which uses Checker Framework dataflow.

To address that, I disabled Error Prone for the versions under which I'd expect the BindingPatternTree code to be a problem.

(I also disabled it for JDK10: As noted above, Error Prone supports JDK11+. And as noted further above, Maven doesn't get far enough with JDK10 to even start running Error Prone.)

Fixes #5801

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