pitfall_5.java

interface Service {	
	Mono<String> create(String s);
	Mono<Void> update(String s);
}
class Foo {
	private final Service service;
	
	Mono<Integer> problem() {
		return service.create("foo").map(foo -> {
			service.update(foo).subscribe();
			return foo.length();
		});
	}
}