Bump nullaway from 0.9.8 to 0.9.9 (#3720)

Bumps [nullaway](https://github.com/uber/NullAway) from 0.9.8 to 0.9.9.
- [Release notes](https://github.com/uber/NullAway/releases)
- [Changelog](https://github.com/uber/NullAway/blob/master/CHANGELOG.md)
- [Commits](uber/NullAway@v0.9.8...v0.9.9)

---
updated-dependencies:
- dependency-name: com.uber.nullaway:nullaway
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

build.gradle

@@ -106,7 +106,7 @@ subprojects {
   /* ERROR PRONE */
   dependencies {
     // NullAway errorprone plugin
-    annotationProcessor 'com.uber.nullaway:nullaway:0.9.8'
+    annotationProcessor 'com.uber.nullaway:nullaway:0.9.9'
     errorprone 'com.google.errorprone:error_prone_core:2.10.0'
     // Using github.com/google/error-prone-javac is required when running on
     // JDK 8. Remove when migrating to JDK 11.