Load FXML files using custom components in JavaFX Scene Builder: reset attributes and children removed

I wrote an FXML file in which I use a custom component that extends Group. When loading this custom component, it must add some child elements (here: MyOverlayIcon) to its children list and set some attributes by code (here: layoutX and layoutY).

MyIcon.java:

public class MyIcon extends Group {

/********************************
 * Graphic
 ********************************/
private ImageView graphic;
public ImageView getGraphic() {
    if(graphic == null) {
        graphic = new ImageView();
        getChildren().add(graphic);
        // Send image to back:
        graphic.toBack();
    }
    return graphic;
}

/********************************
 * DataPath
 ********************************/
private Property<String> dataPath;
public Property<String> dataPathProperty() {
    if (dataPath == null) {
        dataPath = new SimpleStringProperty();
    }
    return dataPath;
}
public String getDataPath() {
    return dataPathProperty().getValue();
}
public void setDataPath(String dataPath) {

    this.dataPathProperty().setValue(dataPath);
    getGraphic().setImage(new Image(dataPath));
}

/********************************
 * Overlays
 ********************************/
private ObservableList<MyOverlayIcon> overlays;
public ObservableList<MyOverlayIcon> getOverlays() {
    if (overlays == null) {
        overlays = FXCollections.observableArrayList();
        overlays.addListener(new ListChangeListener<MyOverlayIcon>() {

            @Override
            public void onChanged(ListChangeListener.Change<? extends MyOverlayIcon> c) {
                double moveX = 0.0;
                double moveY = 0.0;
                double iconWidth = 48.0;
                double iconHeight = 48.0;

                ObservableList<? extends MyOverlayIcon> icons = c.getList();
                MyOverlayIcon icon = icons.get(icons.size() - 1);

                String orientation = icon.getOrientation().toString(); 

                if(orientation.endsWith("EAST")) {
                    moveX = iconWidth / 2; 
                }
                if(orientation.startsWith("SOUTH")) {
                    moveY = iconHeight / 2;
                }

                icon.setLayoutX(moveX);
                icon.setLayoutY(moveY);
                getChildren().add(icon);
            }
        });
    }
    return overlays;
}

/********************************
 * Constructor
 ********************************/
public MyIcon(){}
}

MyOverlayIcon.java:

public class MyOverlayIcon extends MyIcon {

private EnumOrientation orientation;
public EnumOrientation getOrientation() {
    return orientation;
}
public void setOrientation(EnumOrientation orientation) {
    this.orientation = orientation;
    }

public MyOverlayIcon() {}
}

MyIconView.fxml:

<Group xmlns:fx="http://javafx.com/fxml">

    <MyIcon dataPath="@/images/User1_48.png">
        <overlays>
            <MyOverlayIcon dataPath="@/images/Remove_24.png" orientation="SOUTHWEST" />
            <MyOverlayIcon dataPath="@/images/Search1_24.png" orientation="NORTHEAST" />
        </overlays>
    </MyIcon>

</Group>

When I run the application in my IDE by downloading this fxml fith FXMLLoader file, it works fine: all new children are added and displayed correctly:

Now I want to modify this fxml file using Scene Builder. But when I upload a file using Scene Builder, I see only an empty group instance:

Only these two workarounds were detected:

1.) , (, setter-), , , -, , .

2.) Scene Builder , , , , fxml . Scene Builder .

, , java-, , fxml. node fxml, Scene Builder.

: , (: layoutX layoutY), , fxml .

MyIconView_Workaround.fxml:

<Group xmlns:fx="http://javafx.com/fxml">

    <MyIcon dataPath="@/images/User1_48.png">
        <Pane />
        <overlays>
            <MyOverlayIcon dataPath="@/images/Remove_24.png" orientation="SOUTHWEST" layoutY="456">
                <Pane />
            </MyOverlayIcon>
            <MyOverlayIcon dataPath="@/images/Search1_24.png" orientation="NORTHEAST"  layoutX="123">
                <Pane />
            </MyOverlayIcon>
        </overlays>
    </MyIcon>

</Group>

//Edit: , .

- , fxml Scene Builder, , java- ( ) fxml?