Adust to changes in Gerrit core

Change-Id: Ic114e8b4c12a3d9c2474019d16b848ae2243f62f

src/main/java/com/googlesource/gerrit/plugins/singleusergroup/SingleUserGroup.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/singleusergroup/SingleUserGroup.java b/src/main/java/com/googlesource/gerrit/plugins/singleusergroup/SingleUserGroup.java
index f30d0a0..6babe86 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/singleusergroup/SingleUserGroup.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/singleusergroup/SingleUserGroup.java
@@ -158,7 +158,7 @@
   private static GroupReference accountToGroup(AccountState s) {
     AccountGroup.UUID uuid =
         s.userName().isPresent() ? uuid(s.userName().get()) : uuid(s.account().id());
-    return new GroupReference(uuid, nameOf(uuid, s));
+    return GroupReference.create(uuid, nameOf(uuid, s));
   }
 
   private static String username(AccountGroup.UUID uuid) {