public final void debug(Object message, Throwable t) {

        if (isLevelEnabled(SimpleLog.LOG_LEVEL_DEBUG)) {
            log(SimpleLog.LOG_LEVEL_DEBUG, message, t);
        }
    }
<p>
Log an error with debug log level.
jcl-over-slf4j/src/main/java/org/apache/commons/logging/impl/SimpleLog.java