Use getContent() to access the content of the current request, rather…

… than the protected content property

src/Router.php

@@ -137,7 +137,7 @@ public function singleRequest($method, $uri, array $data = [], array $headers =
             $currentRequest->cookies->all(),
             $currentRequest->files->all(),
             $currentRequest->server->all(),
-            $currentRequest->content
+            $currentRequest->getContent()
         );
 
         return $response;