@Override
 public Response createUsersWithArrayInput(User[] users) {
   for (User user : users) {
     userData.addUser(user);
   }
   return Response.ok().entity("").build();
 }
 @Override
 public Response createUsersWithListInput(java.util.List<User> users) {
   for (User user : users) {
     userData.addUser(user);
   }
   return Response.ok().entity("").build();
 }
 @Override
 public Response updateUser(String username, User user) {
   userData.addUser(user);
   return Response.ok().entity("").build();
 }
 @Override
 public Response createUser(User user) {
   userData.addUser(user);
   return Response.ok().entity("").build();
 }