Make SearchingChangeCacheImpl nullable when replicating from slave

SearchingChangeCacheImpl should be nullable in slave mode.

Change-Id: If22407565f44e7ed201e57d7d3b7b9a51f20b5bc

src/main/java/com/googlesource/gerrit/plugins/replication/PushOne.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/PushOne.java b/src/main/java/com/googlesource/gerrit/plugins/replication/PushOne.java
index 48586eb..a251832 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/PushOne.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/PushOne.java
@@ -21,6 +21,7 @@
 import com.google.common.collect.LinkedListMultimap;
 import com.google.common.collect.Multimap;
 import com.google.common.collect.Sets;
+import com.google.gerrit.common.Nullable;
 import com.google.gerrit.extensions.events.GitReferenceUpdatedListener;
 import com.google.gerrit.metrics.Timer1;
 import com.google.gerrit.reviewdb.client.Project;
@@ -128,7 +129,7 @@
       TagCache tc,
       PerThreadRequestScope.Scoper ts,
       ChangeNotes.Factory nf,
-      SearchingChangeCacheImpl cc,
+      @Nullable SearchingChangeCacheImpl cc,
       ReplicationQueue rq,
       IdGenerator ig,
       ReplicationStateListener sl,