Fix injection of the ignoredRef for global-refdb validation

The ignoredRef must be injected as ImmutableSet<String> rather
than Set<String>. The change to the ImmutableSet happened during
the last review of the global-refdb, but the corresponding change
in multi-site was left behind.

This has passed unnoticed because the ignoredRef injection is
optional and therefore just continued with the default value
which is empty = do not ignore any refs.

Change-Id: Ib8f756dc4b336af25149fa4bb6fd5a57acbe1fdb
diff --git a/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/ValidationModule.java b/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/ValidationModule.java
index 16fa09a..fe224ae 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/ValidationModule.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/ValidationModule.java
@@ -41,7 +41,6 @@
 import com.googlesource.gerrit.plugins.multisite.ProjectVersionLogger;
 import com.googlesource.gerrit.plugins.replication.ReplicationExtensionPointModule;
 import com.googlesource.gerrit.plugins.replication.ReplicationPushFilter;
-import java.util.Set;
 
 public class ValidationModule extends FactoryModule {
   private final Configuration cfg;
@@ -67,7 +66,7 @@
     factory(BatchRefUpdateValidator.Factory.class);
 
     bind(SharedRefDbConfiguration.class).toInstance(cfg.getSharedRefDbConfiguration());
-    bind(new TypeLiteral<Set<String>>() {})
+    bind(new TypeLiteral<ImmutableSet<String>>() {})
         .annotatedWith(Names.named(SharedRefDbGitRepositoryManager.IGNORED_REFS))
         .toInstance(
             ImmutableSet.of(