Make PushOne.LockFailureException a static inner class

Change-Id: I3e8a7f4f37ddc7947d8fcaf840227d28cc05a5e9
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 0614959..96156b7 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/PushOne.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/PushOne.java
@@ -611,7 +611,7 @@
     stateMap.clear();
   }
 
-  public class LockFailureException extends TransportException {
+  public static class LockFailureException extends TransportException {
     private static final long serialVersionUID = 1L;
 
     public LockFailureException(URIish uri, String message) {