from docs
Since Spring Framework 5.0, Spring comes with its own Commons Logging bridge implemented in the spring-jcl module. The implementation checks for the presence of the Log4j 2.x API and the SLF4J 1.7 API in the classpath and uses the first one of those found as the logging implementation, falling back to the Java platform’s core logging facilities (also known as JUL or java.util.logging) if neither Log4j 2.x nor SLF4J is available.
Put Log4j 2.x or Logback (or another SLF4J provider) in your classpath, without any extra bridges, and let the framework auto-adapt to your choice. For further information see the Spring Boot Logging Reference Documentation.
public class MyBean {
private final Log log = LogFactory.getLog(getClass());
// ...
}