code: private static void addMarkerLine(String label, Double value, Double offset, Axis axis) {
      if (value != null) {
        MarkerLine markerLine = MarkerLineImpl.create(axis, NumberDataElementImpl.create(value + (offset != null ? offset : 0d)));
        markerLine.getLineAttributes().setStyle(LineStyle.DASHED_LITERAL);
        markerLine.getLabel().getCaption().setValue(label);
        markerLine.setLabelAnchor(Anchor.NORTH_EAST_LITERAL);
      }
    }
docs: Creates a marker line into specified axis if value is not null.
  
  @param label line label
  @param value value
  @param offset value offset
  @param axis axis