activitypub-1.0.x-dev/src/Entity/Storage/ActivityPubActivityStorageSchema.php

<?php

namespace Drupal\activitypub\Entity\Storage;

use Drupal\Core\Entity\Sql\SqlContentEntityStorageSchema;
use Drupal\Core\Field\FieldStorageDefinitionInterface;

/**
 * Defines the ActivityPub Activity schema handler.
 */
class ActivityPubActivityStorageSchema extends SqlContentEntityStorageSchema {

  /**
   * {@inheritdoc}
   */
  protected function getSharedTableFieldSchema(FieldStorageDefinitionInterface $storage_definition, $table_name, array $column_mapping) {
    $schema = parent::getSharedTableFieldSchema($storage_definition, $table_name, $column_mapping);
    $field_name = $storage_definition->getName();

    if ($table_name == $this->storage->getBaseTable()) {
      switch ($field_name) {
        case 'collection':
          $schema['fields'][$field_name]['not null'] = TRUE;
          break;
      }
    }

    return $schema;
  }

}