reactor-core/src/main/java/reactor/util/Loggers.java
public static final void useSl4jLoggers() {
		String name = LoggerFactory.class.getName();
		LoggerFactory loggerFactory = new Slf4JLoggerFactory();
		loggerFactory.getLogger(name).debug("Using Slf4j logging framework");
		LOGGER_FACTORY = loggerFactory;
	}
public static final void useSl4jLoggers() {
		String name = LoggerFactory.class.getName();
		LoggerFactory loggerFactory = new Slf4JLoggerFactory();
		loggerFactory.getLogger(name).debug("Using Slf4j logging framework");
		LOGGER_FACTORY = loggerFactory;
	}
Force the usage of SL4J-based {@link Logger Loggers}, throwing an exception if
SLF4J isn't available on the classpath. Prefer using {@link #resetLoggerFactory()}
as it will fallback in the later case.
<p>
The previously active logger factory is simply replaced without
any particular clean-up.