@Override
 @GET
 @Path("/user/username/{userName}")
 public Response getUserWithUserName(@PathParam("userName") final String userName) {
   try {
     final User user = ticketSystemService.getUserWithUserName(userName);
     return Response.status(200).entity(gson.toJson(user)).build();
   } catch (final TicketSystemServiceException exception) {
     return Response.status(400).entity(exception).build();
   }
 }