Retrieving field with Annotation in JavaFX throws exception

Question

this question might be related to the one I asked here already, but in my opinion it is a continuation of my deliberations and the search for a solution, and therefore written in a new question.

In the discussion that I have linked above, it was possible to create a small reproduction of the code on this question.

    package test;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

@Retention(RetentionPolicy.RUNTIME)
public @interface MyAnno {
}

// End of MyAnno

package test;
import java.lang.reflect.Field;

public class MyTest {
    @MyAnno
    public String someField = "Hi Mom";
    
    public void doIt() throws Exception {
        for (Field field : this.getClass().getDeclaredFields()) {
            if (field.isAnnotationPresent(MyAnno.class)) {
                if (field.getType().getCanonicalName().equals("java.lang.String")) {
                    String value = (String) field.get(this);
                    System.out.println(value);
                }
            }
        }
    }

    public static void main(String[] args) throws Exception {
        new MyTest().doIt();
    }
}

The idde behind the code is to retrieve the value of the field, which has been marked with an annotation. This code works, but why does the same code does not work when I implement it in a JAVAFX? I'll add the one for it below, but it throws the error: Can not set java.lang.String field sample.Controller.str to sample.Controller$1

    package sample;

import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import java.lang.reflect.Field;


public class Controller   {

     @FXML
     private Button button;
     @MyAnno
     String str = "str";


    public void initialize() {
            button.setOnAction(new EventHandler<ActionEvent>() {
                @Override
                public void handle(ActionEvent event) {
                        for (Field field : Controller.class.getDeclaredFields()) {
                            if (field.isAnnotationPresent(MyAnno.class)) {

                                try {
                                    String string = (String) field.get(this);
                                    System.out.println(string);
                                } catch (IllegalAccessException e) {
                                    e.printStackTrace();
                                }

                            }
                        }
                    }


                });
            }
    }

package sample;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

@Retention(RetentionPolicy.RUNTIME)
public @interface MyAnno {
}


package sample;

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

public class Main extends Application {

    Controller controller;


    @Override
    public void start(Stage primaryStage) throws Exception{
        Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
        primaryStage.setTitle("Hello World");
        primaryStage.setScene(new Scene(root, 300, 275));
        primaryStage.show();
    }


    public static void main(String[] args) {
        launch(args);
        Controller controller = new Controller();
        controller.initialize();

    }
}


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

<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.ColumnConstraints?>
<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.layout.RowConstraints?>


<GridPane alignment="center" hgap="10" vgap="10" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/15.0.1" fx:controller="sample.Controller">
   <columnConstraints>
      <ColumnConstraints />
      <ColumnConstraints />
   </columnConstraints>
   <rowConstraints>
      <RowConstraints />
      <RowConstraints />
   </rowConstraints>
   <children>
      <Button fx:id="button" mnemonicParsing="false" text="Button" GridPane.columnIndex="1" GridPane.rowIndex="1" />
   </children>
</GridPane>