Adapt to Branch.NameKey refactoring

Change-Id: I2c6e9f016334645fa1819cd166840f1cfbc3768c
diff --git a/src/main/java/com/googlesource/gerrit/plugins/deleteproject/DeletePreconditions.java b/src/main/java/com/googlesource/gerrit/plugins/deleteproject/DeletePreconditions.java
index 7085768..5bf75c5 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/deleteproject/DeletePreconditions.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/deleteproject/DeletePreconditions.java
@@ -155,7 +155,7 @@
         MergeOpRepoManager mergeOp = mergeOpProvider.get()) {
       Set<Branch.NameKey> branches =
           repo.getRefDatabase().getRefsByPrefix(REFS_HEADS).stream()
-              .map(ref -> new Branch.NameKey(projectNameKey, ref.getName()))
+              .map(ref -> Branch.nameKey(projectNameKey, ref.getName()))
               .collect(toSet());
       SubmoduleOp sub = subOpFactory.create(branches, mergeOp);
       for (Branch.NameKey b : branches) {