Vaadin - How to convert a Grid column which has boolean value to Checkbox

I am using Vaadin 7.6.4 for my UI work. This has the following:-

• I have a window which contains a grid with data in it. This window is actually a kind of a pop up[ which shows up when my main screen gets a click on the settings icon( not shown here). This is working fine( getting the UI screen to open the Vaadin window when the settings icon the main screen is clicked).
• The problem is in showing the data as mentioned below.
• This grid will have 4 columns for which the data comes from a bean container.
• The first column is a boolean field with true/false getting displayed based on the data from the bean container.
• I need to convert this boolean field column into a checkbox with true showing the field as a checkbox with a value selected. If the value is false, then show a checkbox which is not selected.
• I am trying to do that as shown in the code below but I keep getting this checkbox name printed. I dont see the checkbox but the word "checkbox" printed in there?
• This checkbox should be editable. The idea is that the user should be able to select some checkboxes and the ones selected should be shown in a panel ( not shown here). Thus, the checkbox has to be editable.

How do I fix this? The code for the window is shown below

package com.platform28.mybatis;

import java.util.List;

import com.vaadin.data.Item;
import com.vaadin.data.util.BeanItemContainer;
import com.vaadin.data.util.GeneratedPropertyContainer;
import com.vaadin.data.util.PropertyValueGenerator;
import com.vaadin.ui.Button;
import com.vaadin.ui.Button.ClickEvent;
import com.vaadin.ui.Button.ClickListener;
import com.vaadin.ui.CheckBox;
import com.vaadin.ui.Grid;
import com.vaadin.ui.HorizontalLayout;
import com.vaadin.ui.Label;
import com.vaadin.ui.VerticalLayout;
import com.vaadin.ui.Window;
@SuppressWarnings("serial")
public class ConfigPopUp extends Window {
VaadinUtils vaadinUtils = null;

public ConfigPopUp(List<TableColumnData> tblDataLst) {
    vaadinUtils = new VaadinUtils();

    // Some basic content for the window
    VerticalLayout configLayout = new VerticalLayout();
    configLayout.addComponent(new Label("Settings"));
    configLayout.setMargin(true);
    //configLayout.setWidth(null);;
    setContent(configLayout);
    //adding grid.
    List<SettingsColumnData> settingsList = vaadinUtils.processSettingsList(tblDataLst);
    final BeanItemContainer<SettingsColumnData> gridDataSource = new BeanItemContainer<SettingsColumnData>(SettingsColumnData.class, settingsList);

    //change boolean value to checkbox.
    GeneratedPropertyContainer gp = new GeneratedPropertyContainer(gridDataSource);
    gp.addGeneratedProperty("columnDisplayed", new PropertyValueGenerator<CheckBox>() {

        @Override
        public CheckBox getValue(Item item, Object itemId, Object propertyId) {
            boolean currentCheckBoxValue = (boolean) item.getItemProperty("columnDisplayed").getValue();
            CheckBox chkBox = new CheckBox();
            chkBox.setValue(currentCheckBoxValue);
            return chkBox;
        }

        @Override
        public Class<CheckBox> getType() {
            return CheckBox.class;
        }
    });



    Grid settingsGrid = new Grid(gp);
    settingsGrid.setWidth("100%");
    settingsGrid.setSizeFull();
    settingsGrid.setColumnOrder("columnDisplayed", "columnName","columnShortName","columnDescription");
    configLayout.addComponent(settingsGrid);
    //configLayout.setExpandRatio(settingsGrid, 1);

    // Disable the close button
    setClosable(false);

    HorizontalLayout hLayout = new HorizontalLayout();
    hLayout.setSpacing(true);
    hLayout.setMargin(true);

    // Trivial logic for closing the sub-window
    Button ok = new Button("Ok");
    ok.addClickListener(new ClickListener() {
        public void buttonClick(ClickEvent event) {
            close(); // Close the sub-window
        }
    });
    hLayout.addComponent(ok);

    // Trivial logic for closing the sub-window
    Button cancelBtn = new Button("Cancel");
    cancelBtn.addClickListener(new ClickListener() {
        public void buttonClick(ClickEvent event) {
            close(); // Close the sub-window
        }
    });
    hLayout.addComponent(cancelBtn);

    configLayout.addComponent(hLayout);

    // set pop up to center.
    center();
    // should be resizable
    setResizable(true);
    // should not be draggable
    setDraggable(false);
    //set it as modal window
    setModal(true);

    setWidth("50%");

    setHeight("75%");

}

}