add HandleTestLibraries

[xenoterracide]

this should be a superset of HandleTestAssertionLibraries, meaning if you add this, that should be implied (IMHO)

However, things like this should be automatically added as well. Junit injects a file here so it would pragmatically never be null.

    option("NullAway:ExcludedFieldAnnotations", "org.junit.jupiter.api.io.TempDir")

I'm certain there are other annotations too.

[msridhar]

@xenoterracide I'd be open to just baking in some extra excluded field annotations and the like to better handle tests; I think that might be better than us adding yet another option.

[xenoterracide]

up to you ;)