FillPDF in Drupal 8 scratch

FillPdfForm.php

<?php
/**
 * Defines the entity for managing uploaded FillPDF forms.
 *
 * @ContentEntityType(
 *   id = "fillpdf_form",
 *   label = @Translation("FillPDF form"),
 *   admin_permission = "administer pdfs",
 *   base_table = "users",
 *   data_table = "users_field_data",
 *   label_callback = "user_format_name",
 *   translatable = TRUE,
 *   entity_keys = {
 *     "id" = "uid",
 *     "uuid" = "uuid"
 *   },
 *   links = {
 *     "canonical" = "entity.fillpdf_form.canonical",
 *     "edit-form" = "entity.fillpdf_form.edit_form",
 *     "delete-form" = "entity.fillpdf_form.cancel_form",
 *   },
 * )
 */
 class FillPdfForm extends ContentEntityBase {
   
 }