Scene Builder changes "xmlns" from NetBeans to Java 9 when I have Java 8.0.162

My problem is that when I open my file fxml in NetBeans I get these lines of code which are correct:

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

<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.ColumnConstraints?>
<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.layout.RowConstraints?>

<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="345.0" minWidth="200.0" prefHeight="545.0" prefWidth="400.0" xmlns="http://javafx.com/javafx/8.0.141" xmlns:fx="http://javafx.com/fxml/1">
   <children>
      <GridPane layoutY="25.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
        <columnConstraints>

But when I modify the fxml with the Scene builder and save it, I change this particular code part:

• The good one:

  xmlns="http://javafx.com/javafx/8.0.141" xmlns: fx="http://javafx.com/fxml/1" >

• and when I save it changes it for this:

  xmlns="http://javafx.com/javafx/9" xmlns: fx="http://javafx.com/fxml/1"

This causes me to launch an error that sometimes nothing happens but sometimes my application does not open. What can I do so that the Scene Builder does not change the version of the xmlns ?