Enable missing overrides check

Change-Id: Ibb54202e799de67f235d511101ce1ea1a91d5a29
diff --git a/build.gradle b/build.gradle
index 583ae9e..5990aa0 100644
--- a/build.gradle
+++ b/build.gradle
@@ -17,7 +17,8 @@
     '-Xep:ReferenceEquality:OFF',
     '-Xep:ClassCanBeStatic:WARN',
     '-Xep:OperatorPrecedence:WARN',
-    '-Xep:RemoveUnusedImports:WARN']
+    '-Xep:RemoveUnusedImports:WARN',
+    '-Xep:MissingOverride:WARN']
 
 apply from: 'copyAdditionalJctfCommonFiles.gradle'