ReplicationState: Streamline getRefStatus()

Don't call contains() and then get(), use the result from get() to infer
contains().

Change-Id: Ia42f7c552a3408133934616c818b2b39cdc009c3

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

diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/ReplicationState.java b/src/main/java/com/googlesource/gerrit/plugins/replication/ReplicationState.java
index 871ed52..fa65803 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/ReplicationState.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/ReplicationState.java
@@ -140,12 +140,12 @@
   }
 
   private RefReplicationStatus getRefStatus(String project, String ref) {
-    if (!statusByProjectRef.contains(project, ref)) {
-      RefReplicationStatus refStatus = new RefReplicationStatus(project, ref);
+    RefReplicationStatus refStatus = statusByProjectRef.get(project, ref);
+    if (refStatus == null) {
+      refStatus = new RefReplicationStatus(project, ref);
       statusByProjectRef.put(project, ref, refStatus);
-      return refStatus;
     }
-    return statusByProjectRef.get(project, ref);
+    return refStatus;
   }
 
   public void waitForReplication() throws InterruptedException {