public function getIndex(Request $request)
 {
     header("Access-Control-Allow-Origin: *");
     header("Allow: GET, POST, OPTIONS");
     $colaborador = $request->input('colaborador');
     if ($colaborador == null) {
         $users = User::all();
     } else {
         $users = User::where('colaborador', $colaborador)->get();
     }
     return $users;
 }