LibraryItemSettingsForm.php

<?php

namespace Drupal\paragraphs_library\Form;

use Drupal\Core\Form\ConfigFormBase;
use Drupal\Core\Form\FormStateInterface;

/**
 * Form for Paragraphs library item settings.
 */
class LibraryItemSettingsForm extends ConfigFormBase {

  /**
   * {@inheritdoc}
   */
  public function getFormId() {
    return 'paragraphs_library_item_settings';
  }

  /**
   * {@inheritdoc}
   */
  protected function getEditableConfigNames() {
    return [];
  }

  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state) {

    // This exists to make the field UI pages visible and must not be removed.
    $form['account'] = array(
      '#markup' => '<p>' . $this
        ->t('There are no settings yet.') . '</p>',
    );
    return parent::buildForm($form, $form_state);
  }

}