Java FX Injection goes wrong. Built probably wrong

Ok i am going to admit, this is the first time I am working with Gradle.
But I am not new to Java itself.
So I am trying to set up a javaFX GUI for my Project.
I am quite sure my project isnt built perfect.
I got a NullPointerException for all my Control-Elements…
So here is my Code:

plugins {
    id 'java'
    id 'application'
    id 'org.openjfx.javafxplugin' version '0.0.10'


group 'newP'
version '1.0-SNAPSHOT'

sourceCompatibility = 1.8

repositories {

javafx {
    version = "15.0.1"
    modules = [ 'javafx.controls', 'javafx.fxml', '' ]


sourceSets {
    main {
        resources {
            srcDirs = ["src/main/java"]
            includes = ["**/*.fxml"]
dependencies {
    testCompile group: 'junit', name: 'junit', version: '4.12'
    compile group: '', name: 'gson', version: '2.8.5'
    compile group: 'com.fasterxml.jackson.core', name: 'jackson-core', version: '2.8.8'
    compile group: 'com.fasterxml.jackson.core', name: 'jackson-annotations', version: '2.8.8'
    compile group: 'com.fasterxml.jackson.core', name: 'jackson-databind', version: '2.8.8'
    compile 'com.squareup.okhttp:okhttp:2.5.0'
    compile 'javax.mail:mail:1.4.7'
    implementation 'org.openjfx:javafx-graphics:13.0.1'


That was my gradle.built

Now follows my FX-Application:

package newP;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
import javax.mail.MessagingException;

public class BKPR extends Application {

    private Controller controller;

    public static void main(String[] args) {

    public void start(Stage primaryStage) throws IOException, MessagingException, InterruptedException {

        Parent root = FXMLLoader.load(getClass().getResource("View.fxml"));
        primaryStage.setTitle("Hello World");
        Scene scene = new Scene(root);
        primaryStage.setScene(new Scene(root, 300, 275));;
        controller = new Controller(this);

Well… it doesnt work.
I always get an error on line 5 of my built.
And i dont know why!