Remove redundant 'static' modifier on enum

enums are by default static, so do not need to be explicitly
declared so.

Change-Id: I3544b3f02ae82df70de02641798d5d0089969b3a
diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java b/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java
index 1c9cb96..6d85965 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java
@@ -77,7 +77,7 @@
   private final PerThreadRequestScope.Scoper threadScoper;
   private final DestinationConfiguration config;
 
-  protected static enum RetryReason {
+  protected enum RetryReason {
     TRANSPORT_ERROR, COLLISION, REPOSITORY_MISSING;
   }