Maps a Log4j log level to an Agentry log level, as described in the class documentation.
If you have custom log levels, you can subclass this class and override this method to map your custom log levels to Agentry's levels. Otherwise, this method will make a best-guess attempt at mapping custom log levels, based on which of Java's levels the custom levels fall between (for example, if your custom level's integer value is greater than Level.INFO but less than Level.WARNING, it will be treated as equivalent to Level.INFO).