Suppress deprecation warning about using sha1 function

Change-Id: I4e7a01fe930f70bd550fa13460127b901c1cd100
diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/EventsStorage.java b/src/main/java/com/googlesource/gerrit/plugins/replication/EventsStorage.java
index dc2e6e5..384df0a 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/EventsStorage.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/EventsStorage.java
@@ -96,6 +96,7 @@
     return result;
   }
 
+  @SuppressWarnings("deprecation")
   private ObjectId sha1(String s) {
     return ObjectId.fromRaw(Hashing.sha1().hashString(s, UTF_8).asBytes());
   }