public String convert(ILoggingEvent le) {
    List<Marker> markers = le.getMarkers();
    if (markers == null || markers.isEmpty()) {
      return EMPTY;
    } else {
      return markers.toString();
    }
  }
@Test
  public void testWithSeveralChildMarker() {
    Marker marker = markerFactory.getMarker("testParent");
    marker.add(markerFactory.getMarker("child1"));
    marker.add(markerFactory.getMarker("child2"));
    marker.add(markerFactory.getMarker("child3"));
    
    String result = converter.convert(createLoggingEvent(marker));
    
    assertEquals("[testParent [ child1, child2, child3 ]]", result);
  }