code: @NonNull
      public Session<?> getSession() {
          if (sessionConfiguration.getServerToken() != null) {
              return new ServerTokenSession(sessionConfiguration);
          } else if (accessTokenStorage.getAccessToken() != null) {
              return new AccessTokenSession(sessionConfiguration, accessTokenStorage);
          } else {
              throw new IllegalStateException("Tried to call getSession but not logged in or server token set.");
          }
      }
docs: Gets session based on current {@link SessionConfiguration} and {@link AccessTokenStorage}.
  
  @return Session to use with API requests.
  @throws IllegalStateException when not logged in