<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.layout.*?>
<?import javafx.scene.image.*?>

<AnchorPane xmlns:fx="http://javafx.com/fxml" fx:controller="MyController">
  <children>
    <fx:include source="btn.fxml" fx:id="<caret>unknown"/>
  </children>
</AnchorPane>