code: private void createEmptySessionAndSetAsActive(final String name) {
  		validateSessionName(name);
  
  		final HttpSession session = new HttpSession(name, extension.getHttpSessionTokensSet(getSite()));
  		addHttpSession(session);
  		setActiveSession(session);
  	}
docs: Creates an empty session with the given {@code name} and sets it as the active session.
  <p>
  <strong>Note:</strong> It's responsibility of the caller to ensure that no session with the
  given {@code name} already exists.
  
  @param name the name of the session that will be created and set as the active session
  @throws IllegalArgumentException if the {@code name} is {@code null} or an empty string
  @see #addHttpSession(HttpSession)
  @see #setActiveSession(HttpSession)
  @see #isSessionNameUnique(String)