Fix param type

examples/button-clicker/Assets/DiscordController.cs

@@ -68,7 +68,7 @@ public class DiscordController : MonoBehaviour
         onSpectate.Invoke(secret);
     }
 
-    public void RequestCallback(DiscordRpc.JoinRequest request)
+    public void RequestCallback(ref DiscordRpc.JoinRequest request)
     {
         ++callbackCalls;
         Debug.Log(string.Format("Discord: join request {0}#{1}: {2}", request.username, request.discriminator, request.userId));