CommentJsonMigrator: Mark @UsedAt(GOOGLE)

Change-Id: I2d7bed730eeb58199a46c41ea43ee9c1627244b0
diff --git a/java/com/google/gerrit/server/notedb/CommentJsonMigrator.java b/java/com/google/gerrit/server/notedb/CommentJsonMigrator.java
index e122754..8720c36 100644
--- a/java/com/google/gerrit/server/notedb/CommentJsonMigrator.java
+++ b/java/com/google/gerrit/server/notedb/CommentJsonMigrator.java
@@ -26,6 +26,7 @@
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.client.RefNames;
 import com.google.gerrit.reviewdb.client.RevId;
+import com.google.gerrit.server.UsedAt;
 import com.google.gerrit.server.config.AllUsersName;
 import com.google.gerrit.server.config.GerritServerIdProvider;
 import com.google.inject.Inject;
@@ -50,6 +51,7 @@
 import org.eclipse.jgit.transport.ReceiveCommand;
 import org.eclipse.jgit.util.MutableInteger;
 
+@UsedAt(UsedAt.Project.GOOGLE)
 @Singleton
 public class CommentJsonMigrator {
   private static final FluentLogger logger = FluentLogger.forEnclosingClass();