disabledBranchPattern: fix null checking

The orElse API applies to types marked Optional, not types annotated
with jgit's @Nullable API.  Switch to checking null explicitly.

Change-Id: I819dc46fff56585d9861324af41215a8b6df83b8
Reviewed-on: https://chromium-review.googlesource.com/c/infra/gerrit-plugins/chumpdetector/+/6482507
Commit-Queue: Josip Sokcevic <sokcevic@chromium.org>
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>
Auto-Submit: Mike Frysinger <vapier@chromium.org>
diff --git a/src/main/java/com/googlesource/chromium/plugins/chumpdetector/GetProjectChumpConfig.java b/src/main/java/com/googlesource/chromium/plugins/chumpdetector/GetProjectChumpConfig.java
index 0d1ddb7..96dc717 100644
--- a/src/main/java/com/googlesource/chromium/plugins/chumpdetector/GetProjectChumpConfig.java
+++ b/src/main/java/com/googlesource/chromium/plugins/chumpdetector/GetProjectChumpConfig.java
@@ -57,7 +57,10 @@
     r.treeId = cfg.getString(PROJECT, name, "treeId");
     r.statusURL = cfg.getString(PROJECT, name, "statusURL");
     r.enforceCommitQueue = cfg.getBoolean(PROJECT, name, "enforceCommitQueue", false);
-    r.disabledBranchPattern = cfg.getString(PROJECT, name, "disabledBranchPattern").orElse("^refs/meta/config$");
+    r.disabledBranchPattern = cfg.getString(PROJECT, name, "disabledBranchPattern")
+    if (r.disabledBranchPattern == null) {
+      r.disabledBranchPattern = "^refs/meta/config$";
+    }
     r.preloadImageURL = cfg.getString(PROJECT, name, "preloadImageURL");
     return Response.ok(r);
   }