Jython is not loading the fxml file

This is the test.fxml:

<?xml version="1.0" encoding="UTF-8"?>    
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.BorderPane?>

<BorderPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.171" xmlns:fx="http://javafx.com/fxml/1">
    <center>
        <Label text="It is all OK" BorderPane.alignment="CENTER" />
    </center>
</BorderPane>

I did a Main.java that launchs the window, like follow:

import java.io.IOException;
import java.net.URL;
import javafx.application.Application; 
import javafx.fxml.FXMLLoader;
import javafx.stage.Stage;
import javafx.scene.Parent;
import javafx.scene.Scene;

public class Main extends Application {
    public static void main(String args[]) { 
        launch(args); 
    } 

    public void start(Stage stage) {
        try {
            URL url = this.getClass().getResource("/test.fxml");
            Parent root = FXMLLoader.load(url);
            Scene scene = new Scene(root);
            stage.setScene(scene);
            stage.show();
        } catch (Exception e) {
            // ignore
        }
    }
}

It works.

But the main.py just can not launch and it is almost equal to Main.java.

I did 2 versions of this file that launchs different errors.

This is the first version:

import sys

from java.io import IOException
from java.net import URL
from javafx.application import Application
from javafx.fxml import FXMLLoader
from javafx.stage import Stage
from javafx.scene import Parent
from javafx.scene import Scene

class Main(Application):
@classmethod
def main(cls, args):
    Main.launch(cls, args)

def start(self, stage):
    try:
        url = self.getClass().getResource('/test.fxml')
        root = FXMLLoader.load(url)
        scene = Scene(root)
        stage.setScene(scene)
        stage.show()
    except Exception as exc:
        pass

if __name__ == '__main__':
    Main.main(sys.argv)

That shows:

    Exception in Application start method
    Traceback (most recent call last):
      File "/home/flima/dev/db/herbalife/sell/main.py", line 48, in 
        Main.main(sys.argv)
      File "/home/flima/dev/db/herbalife/sell/main.py", line 29, in main
        Main.launch(cls, args)
        at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
        at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$154(LauncherImpl.java:182)
        at java.lang.Thread.run(Thread.java:748)
    Caused by: java.lang.NullPointerException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)

    java.lang.RuntimeException: java.lang.RuntimeException: Exception in Application start method

This is the second version:

import sys

from java.io import IOException
from java.net import URL
from javafx.application import Application
from javafx.fxml import FXMLLoader
from javafx.stage import Stage
from javafx.scene import Parent
from javafx.scene import Scene

class Main(Application):
@classmethod
def main(cls, args):
    Main.launch(cls, args)

def start(self, stage):
    try:
        url = self.getClass().getResource('/test.fxml')
        self.loader = FXMLLoader(url) # changed here
        root = self.loader.load()     # changed here
        scene = Scene(root)
        stage.setScene(scene)
        stage.show()
    except Exception as exc:
        pass

if __name__ == '__main__':
    Main.main(sys.argv)

I get another error, that is:

    Exception in Application start method
    Traceback (most recent call last):
      File "/home/flima/dev/db/herbalife/sell/main.py", line 48, in 
        Main.main(sys.argv)
      File "/home/flima/dev/db/herbalife/sell/main.py", line 29, in main
        Main.launch(cls, args)
        at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
        at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$154(LauncherImpl.java:182)
        at java.lang.Thread.run(Thread.java:748)
    Caused by: java.lang.IllegalStateException: Location is not set.
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2434)
        at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2409)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)

    java.lang.RuntimeException: java.lang.RuntimeException: Exception in Application start method

Where is my mistake?

All the files are in the same folder.

Please, help me. Thanks.

Jython version is:

Jython 2.7.0 (default:9987c746f838, Apr 29 2015, 02:25:11)

Java version is:

java version "1.8.0_191" Java(TM) SE Runtime Environment (build 1.8.0_191-b12) Java HotSpot(TM) 64-Bit Server VM (build 25.191-b12, mixed mode)

I am running the code at Lubuntu based on Ubuntu 18.04.1 LTS.