How can I set validation rules on my entity fields and get errors if the data isn't valid

I have this entity which got the link field

This link is mandatory, has to be more than 3 chars and less than 255 Also it has to be a valid URL

class Myentity extends ContentEntityBase implements BaseEntityInterface {

  use EntityChangedTrait;

  public static function baseFieldDefinitions( EntityTypeInterface $entity_type )
  {
    $fields = parent::baseFieldDefinitions($entity_type);

    $fields['link'] = BaseFieldDefinition::create('string')
      ->setLabel(t('Url'))
      ->setDescription(t('The entity url.'))
      ->setSettings(
        [
          'default_value' => '',
          'min_length' => 3,
          'max_length' => 255,
          'text_processing' => 0,
        ]
      )->setRequired(true)
      ->addConstraint('Length', ['min' => 3, 'max' => 255]);

  }


}

And then somewhere in the application, I want to save that entity

$data = ['link': 'X'];

$entity = Myentity::create($data);

$violationList = $entity->validate();

echo $violationList->count(); //Prints 0 ! although the length isn't good!

setRequired(true) guarantees me that the field link is mandatory

addConstraint('Length', ['min' => 3, 'max' => 255]) Doesn't seem to work, As I didn't get any error while validating my data

So I've some questions about this code:

1. How do we set the validation rules for an entity, I saw two functions addConstraint and setPropertyConstraints. which one to use or there is another way ?

2. After validating data, and if $violationList->count() is positive, How do we get the rules that failed, I know $violationList->getFieldNames() returns the invalid field but not the rule that failed.

3. And last, what are the rules that Drupal 9 provides, are they the ones that are shipped with the Symfony Validator components as stated in Drupal's documentation OR there is a defined list.

I use addConstraint in my custom entities and haven't had a problem. I see your field definition is for "name" but your data says "link", maybe that's why?

Here's a snippet for getting the errors:

    $violations = $entity->validate();
    $errors = [];
    foreach ($violations as $violation) {
      $property = $violation->getPropertyPath();
      $field = explode('.', $property)[0];
      $label = $entity->get($field)->getFieldDefinition()->getLabel();
      $errors[] = $label . ': ' . $violation->getMessage();
    }

There's a list of core constraints here:

https://api.drupal.org/api/drupal/vendor!symfony!validator!ConstraintValidator.php/class/uses/ConstraintValidator/9.3.x