
<configuration>

  <define name="INCLUDED_FILE_EXISTS" 
          class="ch.qos.logback.core.property.FileExistsPropertyDefiner">
      <path>src/test/input/joran/conditional/includedFile.xml</path>
  </define>
  
   <if condition='property("INCLUDED_FILE_EXISTS").equals("true")'>
    <then>
        <include file="src/test/input/joran/conditional/includedFile.xml"/>
    </then>
  </if> 
</configuration>