ADDITIONAL SYSTEM INFORMATION :
OS: Ubuntu 18.04 / Windows 10 Pro 1709 64bit
Java: Java 8 Update 181

A DESCRIPTION OF THE PROBLEM :
When WebEngine.load() is called, .packagename.mainClassname folder is crated in my $HOME folder.
On Windows, %HOMEPATH%\AppData\Roaming\packagename.mainClassname folder is created.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Create a WebEngine object.
Call WebEngine.load().
Stage.show() is not needed.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
A window is shown without creating any folder.
ACTUAL -
A window is shown, but .bugreport.Main folder is crated in my $HOME folder.
It has a structure as follows:
.bugreport.Main - webview - localstorage(empty folder), .lock(empty file)

On Windows, %HOMEPATH%\AppData\Roaming\bugreport.Main folder is created.

---------- BEGIN SOURCE ----------
package bugreport;

import javafx.application.Application;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.web.WebEngine;
import javafx.scene.web.WebView;

public class Main extends Application {
@Override
public void start(Stage primaryStage) {
try {
WebView root = new WebView();
WebEngine engine = root.getEngine();
engine.load(getClass().getResource("BugReport.html").toString()); // the folder is created here!

Scene scene = new Scene(root,400,400);
primaryStage.setScene(scene);
primaryStage.show();
} catch(Exception e) {
e.printStackTrace();
}
}

public static void main(String[] args) {
launch(args);
}
}

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

FREQUENCY : always