ADDITIONAL SYSTEM INFORMATION :
Windows 10
Java 11.0.4

A DESCRIPTION OF THE PROBLEM :
On Windows, if you have a confirmation dialog with a CheckBox as it's content:
If you click on the checkbox and then hit enter, the checkbox is checked rather than the confirmation dialog closing.
This seems to be a regression from Java 1.8 where it would close the confirmation dialog.

Note also that the Mac doesn't suffer from this same behaviour.

REGRESSION : Last worked in version 11

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the attached example source code
Select the checkbox
Hit Enter
Notice that the dialog doesn't close

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The dialog should close after hitting the enter key
ACTUAL -
The dialog stays open and the checkbox is ticked instead

---------- BEGIN SOURCE ----------
import java.util.Optional;

import javafx.application.Application;
import javafx.scene.control.Alert;
import javafx.scene.control.Alert.AlertType;
import javafx.scene.control.ButtonType;
import javafx.scene.control.CheckBox;
import javafx.stage.Stage;

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

    @Override
    public void start(
        Stage primaryStage)
    {
        showDialog();
    }
    
    private void showDialog()
    {
        Alert alert = new Alert(AlertType.CONFIRMATION);
        alert.setTitle("Confirmation Dialog");
        alert.setHeaderText("Look, a Confirmation Dialog");
        alert.setContentText("Are you ok with this?");
        alert.getDialogPane().setContent(new CheckBox());

        
        Optional<ButtonType> result = alert.showAndWait();
        if (result.get() == ButtonType.OK)
        {
            System.out.println("OK");
        }
        else
        {
            System.out.println("Cancel");
        }
    }
}

---------- END SOURCE ----------

FREQUENCY : always