The RootLoggerModelHandler class is part of the logback library, which is a powerful and flexible logging framework for Java applications. The RootLoggerModelHandler class is used to handle the configuration of the root logger, which is the top-level logger in the logging hierarchy.

Here is an example of how you might use the RootLoggerModelHandler class to configure the root logger:

import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.joran.JoranConfigurator;
import ch.qos.logback.core.joran.spi.JoranException;
import org.slf4j.LoggerFactory;

public class RootLoggerExample {
    public static void main(String[] args) throws JoranException {
        LoggerContext context = (LoggerContext) LoggerFactory.getILoggerFactory();
        JoranConfigurator configurator = new JoranConfigurator();
        configurator.setContext(context);
        context.reset();
        configurator.doConfigure("path/to/logback.xml");

        // now you can use the root logger
        org.slf4j.Logger logger = LoggerFactory.getLogger(RootLoggerExample.class);
        logger.debug("Hello, root logger!");
    }
}

This example first sets up a LoggerContext and a JoranConfigurator and using them to configure the root logger using a logback configuration file ("path/to/logback.xml").

Then you can use the root logger using slf4j's LoggerFactory.getLogger()

It is important to notice that the logback.xml file is a logback configuration file, the configuration in this file should define the appenders and level for the root logger so it can be used.

Also, this is a quite general example and it may need adjustments depending on your specific use case.