reactor-core/src/main/java/reactor/core/publisher/Mono.java
public final Mono<T> log(Logger logger) {
		return log(logger, Level.INFO, false);
	}
public final Mono<T> log(Logger logger) {
		return log(logger, Level.INFO, false);
	}
Observe Reactive Streams signals matching the passed filter {@code options} and
trace them using a specific user-provided {@link Logger}, at {@link Level#INFO} level.
<p>
<img class="marble" src="doc-files/marbles/logForMono.svg" alt="">

@param logger the {@link Logger} to use, instead of resolving one through a category.

@return a new {@link Mono} that logs signals