ClassAbstractLoggerAn abstract implementation which delegates actual logging work to the {@link #handleNormalizedLoggingCall(Level, Marker, String, Object[], Throwable)}
slf4j-api/src/main/java/org/slf4j/helpers/AbstractLogger.java:42
ClassLevelDefines the minimum set of levels recognized by the system, that is <code>OFF</code>, <code>FATAL</code>, <code>ERROR</code>, <code>WARN</code>, <code
log4j-over-slf4j/src/main/java/org/apache/log4j/Level.java:39