docs: public void addUserInUserManager(User user) {
          if (!userManager.getUserList().contains(user.getUsername())) {
              try {
                  userManager.createUser(user.getUsername());
              } catch (UserExistsException e) {
                  LOGGER.warn("User already exists!", e);
                  return;
              }
          }
          for (Attribute attribute : user.getAttributes()) {
              userManager.setUserAttribute(user.getUsername(), attribute.getAttributeName(), attribute.getValues()
                      .toArray());
          }
      }