code: public static RedmineManager createWithUserAuth(String uri, String login,
                                                      String password, HttpClient httpClient) {
          final Transport transport = new Transport(
                  new URIConfigurator(uri, null), httpClient);
          transport.setCredentials(login, password);
          return new RedmineManager(transport);
      }
docs: Creates a new redmine managen with user-based authentication.
  
  @param uri      redmine manager URI.
  @param login    user's name.
  @param password user's password.
  @param httpClient you can provide your own pre-configured HttpClient if you want
  to control connection pooling, manage connections eviction, closing, etc.