async getItem(itemPosition) {
        const items = await $(this.rootElement).$$('[data-id="input-checkbox_container"]');
        if (items[itemPosition]) {
            return new PageCheckboxItem(
                `${
                    this.rootElement
                } [data-id="input-checkboxgroup_container"]:nth-child(${itemPosition + 1})`,
            );
        }
        return null;
    }
Returns a new Checkbox page object of the element in item position.
@method
@param {number} itemPosition - The base 0 index of the checkbox.