LOGBACK get entire log entry in custom appender

Question

I have following logback configuration in my project:

<?xml version="1.0" encoding="UTF-8"?>
<configuration status="WARN">

    <!-- Define the appenders -->
    <appender name="Console" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%highlight{%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n}</pattern>
        </encoder>
    </appender>

    <appender name="SimpleAppender" class="com.simple.SimpleAppender2">
        <layout class="ch.qos.logback.classic.PatternLayout">
            <pattern>%d{HH:mm:ss.SSS} - [ %-5level] - %msg%n</pattern>
        </layout>
    </appender>

    <!-- Define the loggers -->
    <logger name="SimpleLogger" level="INFO">
        <appender-ref ref="SimpleAppender" />
    </logger>

    <!-- Define the root logger -->
    <root level="INFO">
        <appender-ref ref="Console" />
    </root>
</configuration>

In my SimpleAppender I want get entire log message formatted by pattern from appender: %d{HH:mm:ss.SSS} - [ %-5level] - %msg%n

public class SimpleAppender2 extends AppenderBase<ILoggingEvent> {
     @Override
    protected void append(ILoggingEvent event) {
       // get log message formatted by pattern from config
    }
}

How can I do this ?