How to properly check in entity form validation if field is empty?
I think I found what I was looking for, ContentEntityForm does it like this:

/** @var \Drupal\Core\Entity\ContentEntityInterface $entity */
$entity = $this-&gt;buildEntity($form, $form_state);
$violations = $entity-&gt;validate();


All I have to do is building the entity, after that I have to just check the right field, which has already the ability to tell per fields if they are empty or not. (since each field is knowing it's type and also how to check if there is a value or not)