code: @Override
      public FilterReply decide(final ILoggingEvent event) {
          final Marker marker = event.getMarker();
  
          if (marker == this.marker) {
              return FilterReply.NEUTRAL;
          } else {
              return FilterReply.DENY;
          }
      }
docs: Filter the logging event according to the provided marker
  @param event The logging event
  @return FilterReply.NEUTRAL if the event's marker is the same as the provided marker; FilterReply.DENY otherwise