Resolve #3240801 "Data loss occurs"

    // Check if we are editing the field or is new.

    $is_new = $this->isNewValue($form_state);

    // And get therefore the values depending also if the submit has failed.

    $selected_values = $this->getSelectedOptions($form_state->getUserInput(), $items, $rating_options, $is_new);

    $selected_values = $this->getSelectedOptions($form_state->getUserInput(), $items, $questions, $is_new);

    // And add to the list.

    $element['#values'] = $selected_values;

   *   Array of all the inputs of the user from the form_state.

   * @param \Drupal\Core\Field\FieldItemListInterface $items

   *   The field values.

   * @param array $rating_options

   *   The rating options of the field from the element.

   * @param array $questions

   *   The questions of the field from the element.

   * @param bool $is_new

   *   Flaf to indicate if the field is being edited or not.

   *

   * @return array

   *   Normal array with the inputs of the radios on each row.

   */

  protected function getSelectedOptions(array $user_input, FieldItemListInterface $items, array $rating_options, $is_new) {

  protected function getSelectedOptions(array $user_input, FieldItemListInterface $items, array $questions, $is_new) {

    $values = [];

    // First we check if the field has been submitted and failed.

    // It has the latest value of the field.

    foreach ($rating_options as $key => $option) {

    foreach ($questions as $key => $option) {

      // We just check if the field exists, meaning any radio has been selected.

      if (isset($user_input[$this->fieldName . '-row-' . $key])) {

        // Yes, so we get the value from the input array.