web/src/main/java/org/springframework/security/web/csrf/LazyCsrfTokenRepository.java
@Override
	public void saveToken(CsrfToken token, HttpServletRequest request,
			HttpServletResponse response) {
		if (token == null) {
			this.delegate.saveToken(token, request, response);
		}
	}
@Override
	public void saveToken(CsrfToken token, HttpServletRequest request,
			HttpServletResponse response) {
		if (token == null) {
			this.delegate.saveToken(token, request, response);
		}
	}
Does nothing if the {@link CsrfToken} is not null. Saving is done only when the
{@link CsrfToken#getToken()} is accessed from
{@link #generateToken(HttpServletRequest)}. If it is null, then the save is
performed immediately.