Adjust to 2.16 API

Since 6b6afe2681 CreateBranch is a Singleton and can be directly
injected rather than being created via a factory.

Change-Id: I51ba1b82ec0986ed643b444885fbac175582ec8e

src/main/java/com/googlesource/gerrit/plugins/refprotection/BackupRef.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/refprotection/BackupRef.java b/src/main/java/com/googlesource/gerrit/plugins/refprotection/BackupRef.java
index dd4e21b..d4af191 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/refprotection/BackupRef.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/refprotection/BackupRef.java
@@ -31,6 +31,7 @@
 import com.google.gerrit.extensions.api.projects.BranchInput;
 import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.extensions.restapi.BadRequestException;
+import com.google.gerrit.extensions.restapi.IdString;
 import com.google.gerrit.extensions.restapi.ResourceConflictException;
 import com.google.gerrit.server.config.PluginConfigFactory;
 import com.google.gerrit.server.data.AccountAttribute;
@@ -64,14 +65,14 @@
 public class BackupRef {
   public static final String R_BACKUPS = R_REFS + "backups/";
   private static final Logger log = LoggerFactory.getLogger(BackupRef.class);
-  private final CreateBranch.Factory createBranchFactory;
+  private final CreateBranch createBranch;
   @Inject private static PluginConfigFactory cfg;
   @Inject private static GitRepositoryManager repoManager;
   @Inject @PluginName private static String pluginName;
 
   @Inject
-  BackupRef(CreateBranch.Factory createBranchFactory) {
-    this.createBranchFactory = createBranchFactory;
+  BackupRef(CreateBranch createBranch) {
+    this.createBranch = createBranch;
   }
 
   public void createBackup(RefUpdatedEvent event, ProjectResource project) {
@@ -163,7 +164,7 @@
               ObjectId.toString(revWalk.parseCommit(ObjectId.fromString(refUpdate.oldRev)).getId());
 
           try {
-            createBranchFactory.create(backupRef).apply(project, input);
+            createBranch.apply(project, IdString.fromDecoded(backupRef), input);
           } catch (BadRequestException
               | AuthException
               | ResourceConflictException