[4.x] REST API Globals return resolved relations (#8555)

Co-authored-by: Jason Varga <jason@pixelfear.com>

src/Http/Resources/API/GlobalSetResource.php

@@ -7,6 +7,9 @@
 
 class GlobalSetResource extends JsonResource
 {
+    /** @deprecated */
+    private static $relations = false;
+
     /**
      * Transform the resource into an array.
      *
@@ -15,13 +18,29 @@ class GlobalSetResource extends JsonResource
      */
     public function toArray($request)
     {
-        return $this->resource
+        $collection = $this->resource
             ->toAugmentedCollection()
             ->merge([
                 'handle' => $this->resource->handle(),
                 'api_url' => Statamic::apiRoute('globals.show', [$this->resource->handle()]),
-            ])
+            ]);
+
+        if (static::$relations) {
+            $with = $this->resource->blueprint()
+                ->fields()->all()
+                ->filter->isRelationship()->keys()->all();
+
+            $collection->withRelations($with);
+        }
+
+        return $collection
             ->withShallowNesting()
             ->toArray();
     }
+
+    /** @deprecated */
+    public static function withRelations()
+    {
+        static::$relations = true;
+    }
 }