Here is an example of how you can use the LogbackMDCAdapterSimple class from the logback.classic package:

import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.spi.LoggingEvent;
import ch.qos.logback.classic.util.LogbackMDCAdapterSimple;
import org.slf4j.LoggerFactory;

public class MyClass {
  public static void main(String[] args) {
    // Get the logger
    Logger logger = (Logger) LoggerFactory.getLogger(MyClass.class);

    // Get the logger context
    LoggerContext context = logger.getLoggerContext();

    // Create a LogbackMDCAdapterSimple instance
    LogbackMDCAdapterSimple mdcAdapter = new LogbackMDCAdapterSimple(context);

    // Set a value in the MDC
    mdcAdapter.put("key", "value");

    // Create a logging event
    LoggingEvent event = new LoggingEvent();

    // Copy the MDC data to the logging event
    mdcAdapter.getPropertyMap().forEach((k, v) -> event.setMDCProperty(k, v));
  }
}

The LogbackMDCAdapterSimple class is a simple implementation of the MDCAdapter interface that can be used to store diagnostic context information in a LoggingEvent. The MDC (Mapped Diagnostic Context) is a thread-local map that can be used to store contextual information about a request that can be used in log messages.

In this example, we create a LogbackMDCAdapterSimple instance and use the put method to set a value in the MDC. We then create a LoggingEvent instance and use the getPropertyMap method to get the MDC data as a map. Finally, we use the setMDCProperty method to copy the MDC data to the logging event.