EntityTaxonomyVocabulary.php

<?php

declare (strict_types=1);
namespace Drupal\taxonomy\Plugin\migrate\destination;

use Drupal\migrate\Attribute\MigrateDestination;
use Drupal\migrate\Plugin\migrate\destination\EntityConfigBase;
use Drupal\migrate\Row;

/**
 * Migration destination for taxonomy vocabulary.
 */
class EntityTaxonomyVocabulary extends EntityConfigBase {
    
    /**
     * {@inheritdoc}
     */
    public function getEntity(Row $row, array $old_destination_id_values) {
        
        /** @var \Drupal\taxonomy\VocabularyInterface $vocabulary */
        $vocabulary = parent::getEntity($row, $old_destination_id_values);
        // Config schema does not allow description to be empty.
        if (trim($vocabulary->getDescription()) === '') {
            $vocabulary->set('description', NULL);
        }
        return $vocabulary;
    }

}