Upgrade error_prone_core to 2.2.0

Change-Id: Icf1e2fba724dec363bdc941e562396255b9d9faf
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

pom.xml

@@ -318,7 +318,7 @@
             <dependency>
               <groupId>com.google.errorprone</groupId>
               <artifactId>error_prone_core</artifactId>
-              <version>2.1.3</version>
+              <version>2.2.0</version>
             </dependency>
           </dependencies>
         </plugin>