Upgrade to error-prone 2.16

Release notes:

https://github.com/google/error-prone/releases/tag/v2.16

pom.xml

@@ -165,7 +165,7 @@
             <path>
               <groupId>com.google.errorprone</groupId>
               <artifactId>error_prone_core</artifactId>
-              <version>2.15.0</version>
+              <version>2.16</version>
             </path>
           </annotationProcessorPaths>
         </configuration>