Lucius Digital: Multiple files upload in a custom Drupal form programmatically | Native, clean example Drupal code

Multiple files upload in a custom Drupal form programmatically | Native, clean example Drupal code
Last blog post I shared how to implement rich text in a custom Drupal 9 form, I faced similar issue with files in OpenLucius: couldn’t find native, clean and complete working example for multiple files upload. So I figured it out, here is the example code: