<configuration>

  <evaluator name="DISPLAY_CALLER_EVAL">
    <expression>
      logger.contains("chapters.layouts") &amp;&amp; message.contains("who calls thee")
    </expression>
  </evaluator>

  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
    <encoder>
      <pattern>%-4relative [%thread] %-5level - %msg%n%caller{2, DISPLAY_CALLER_EVAL}</pattern> 
    </encoder>
  </appender>

  <root level="DEBUG">
    <appender-ref ref="STDOUT" />
  </root>
</configuration>