Spring Removed unnecessary function call in Mono.switchIfEmpty()

In this code, the 'switchIfEmpty()' method always calls createWebSession(). If this is unintentional, it needs to be fix.

return Mono.defer(() -> retrieveSession(exchange)
        .switchIfEmpty(createWebSession())
        .doOnNext(session -> exchange.getResponse().beforeCommit(() -> save(exchange, session))));

Please review and let me know if I misunderstood.