private void reportUnknownLevel(Level jplLevel) {
        String message = "Unknown log level [" + jplLevel + "]";
        IllegalArgumentException iae = new IllegalArgumentException(message);
        Reporter.error("Unsupported log level", iae);
    }
<p>Level.OFF and Level.ALL levels are not supposed to be used when calling log printing methods.
</p>

<p>We compensate for such incorrect usage by transforming Level.OFF as Level.ERROR and
Level.ALL as Level.TRACE.
</p>

@param jplLevel
@return
slf4j-jdk-platform-logging/src/main/java/org/slf4j/jdk/platform/logging/SLF4JPlatformLogger.java