Adapt to enabling CheckReturnValue in gerrit core.

Bug: Google b/312699566
Change-Id: I72baf8ef263fc7476a8b4823f3a3d5af3d35257b
Signed-off-by: Edwin Kempin <ekempin@google.com>

src/main/java/com/googlesource/gerrit/plugins/deleteproject/HideProject.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/deleteproject/HideProject.java b/src/main/java/com/googlesource/gerrit/plugins/deleteproject/HideProject.java
index 4716c5b..ff5bb88 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/deleteproject/HideProject.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/deleteproject/HideProject.java
@@ -83,7 +83,9 @@
   private void createProjectIfMissing(String projectName) throws IOException, RestApiException {
     if (!projectCache.get(Project.nameKey(projectName)).isPresent()) {
       try {
-        createProject.apply(TopLevelResource.INSTANCE, IdString.fromDecoded(projectName), null);
+        @SuppressWarnings("unused")
+        var unused =
+            createProject.apply(TopLevelResource.INSTANCE, IdString.fromDecoded(projectName), null);
       } catch (RestApiException | ConfigInvalidException | PermissionBackendException e) {
         throw new ResourceConflictException(
             String.format("Failed to create project %s", projectName), e);