Merge pull request #16438 from drawmyattention/patch-1

[5.3] Support custom primary keys on User model

src/Illuminate/Broadcasting/Broadcasters/PusherBroadcaster.php

@@ -67,7 +67,7 @@ public function validAuthenticationResponse($request, $result)
         } else {
             return $this->decodePusherResponse(
                 $this->pusher->presence_auth(
-                    $request->channel_name, $request->socket_id, $request->user()->id, $result)
+                    $request->channel_name, $request->socket_id, $request->user()->getKey(), $result)
             );
         }
     }