Update to JSpecify 0.3.0-alpha-1

[msridhar]

The artifact now contains @NullMarked and @NullUnmarked annotations, so we do not need to create our own for testing.

[coveralls]

Pull Request Test Coverage Report for Build #999

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.04%) to 92.869%

---

Files with Coverage Reduction	New Missed Lines	%
../nullaway/src/main/java/com/uber/nullaway/dataflow/AccessPath.java	2	95.77%

Totals
Change from base Build #998:	-0.04%
Covered Lines:	5079
Relevant Lines:	5469

---

💛 - Coveralls

[lazaroclapp]

Upstream @Null[Un]Marked annotations have ElementKind.MODULE scope, which is not compatible with JDK8. We might not be able to make this change until we deprecate Java 8 support...

[msridhar]

Upstream @Null[Un]Marked annotations have ElementKind.MODULE scope, which is not compatible with JDK8. We might not be able to make this change until we deprecate Java 8 support...

You're right. I filed jspecify/jspecify#302 just to check if this was intended behavior.

[msridhar]

@lazaroclapp we can work around the JDK 8 javac issue by using Error Prone javac when building on JDK 8. So I think this is ready for review.

[msridhar]

Moving this since we can't compile with -Werror on JDK 8 anymore (due to warnings caused by jspecify annotations)

[lazaroclapp]

LGTM!