Use Error Prone version 2.9.0

build.gradle

@@ -690,13 +690,13 @@ subprojects {
         //  * Uncomment "-Werror"
         //  * Don't edit framework/build.gradle to use the same version number
         //    (it is updated when the annotated version of Guava is updated).
-        errorprone group: 'com.google.errorprone', name: 'error_prone_core', version: '2.8.1'
+        errorprone group: 'com.google.errorprone', name: 'error_prone_core', version: '2.9.0'
 
       // TODO: it's a bug that annotatedlib:guava requires the error_prone_annotations dependency.
       // Update the next two version numbers in tandem.  Get the Error Prone version from the "compile
       // dependencies" section of https://mvnrepository.com/artifact/com.google.guava/guava/30.1.1-jre .
       // (It isn't at https://mvnrepository.com/artifact/org.checkerframework.annotatedlib/guava/30.1.1-jre, which is the bug.)
-      annotatedGuava 'com.google.errorprone:error_prone_annotations:2.8.1'
+      annotatedGuava 'com.google.errorprone:error_prone_annotations:2.9.0'
       annotatedGuava ('org.checkerframework.annotatedlib:guava:30.1.1-jre') {
         // So long as Guava only uses annotations from checker-qual, excluding it should not cause problems.
         exclude group: 'org.checkerframework'