class ConfigEntityType

class ConfigEntityType extends EntityType implements ConfigEntityTypeInterface {
    
    /**
     * The config prefix set in the configuration entity type annotation.
     *
     * @var string
     *
     * @see \Drupal\Core\Config\Entity\ConfigEntityTypeInterface::getConfigPrefix()
     */
    protected $config_prefix;
    
    /**
     * {@inheritdoc}
     */
    protected $static_cache = FALSE;
    
    /**
     * Keys that are stored key value store for fast lookup.
     *
     * @var array
     */
    protected $lookup_keys = [];
    
    /**
     * The list of configuration entity properties to export from the annotation.
     *
     * @var array
     */
    protected $config_export = [];
    
    /**
     * The result of merging config_export annotation with the defaults.
     *
     * This is stored on the class so that it does not have to be recalculated.
     *
     * @var array
     */
    protected $mergedConfigExport = [];
    
    /**
     * {@inheritdoc}
     *
     * @throws \Drupal\Core\Config\Entity\Exception\ConfigEntityStorageClassException
     *   Exception thrown when the provided class is not an instance of
     *   \Drupal\Core\Config\Entity\ConfigEntityStorage.
     */
    public function __construct($definition) {
        // Ensure a default list cache tag is set; do this before calling the parent
        // constructor, because we want "Configuration System style" cache tags.
        if (empty($this->list_cache_tags)) {
            $this->list_cache_tags = [
                'config:' . $definition['id'] . '_list',
            ];
        }
        parent::__construct($definition);
        // Always add a default 'uuid' key.
        $this->entity_keys['uuid'] = 'uuid';
        $this->entity_keys['langcode'] = 'langcode';
        $this->handlers += [
            'storage' => 'Drupal\\Core\\Config\\Entity\\ConfigEntityStorage',
        ];
        $this->lookup_keys[] = 'uuid';
    }
    
    /**
     * {@inheritdoc}
     */
    public function getConfigPrefix() {
        // Ensure that all configuration entities are prefixed by the name of the
        // module that provides the configuration entity type.
        if (isset($this->config_prefix)) {
            $config_prefix = $this->provider . '.' . $this->config_prefix;
        }
        else {
            $config_prefix = $this->provider . '.' . $this->id();
        }
        if (strlen($config_prefix) > static::PREFIX_LENGTH) {
            throw new ConfigPrefixLengthException("The configuration file name prefix {$config_prefix} exceeds the maximum character limit of " . static::PREFIX_LENGTH);
        }
        return $config_prefix;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getBaseTable() {
        return FALSE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getRevisionDataTable() {
        return FALSE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getRevisionTable() {
        return FALSE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getDataTable() {
        return FALSE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getConfigDependencyKey() {
        return 'config';
    }
    
    /**
     * {@inheritdoc}
     *
     * @throws \Drupal\Core\Config\Entity\Exception\ConfigEntityStorageClassException
     *   Exception thrown when the provided class is not an instance of
     *   \Drupal\Core\Config\Entity\ConfigEntityStorage.
     *
     * @see \Drupal\Core\Config\Entity\ConfigEntityStorage
     */
    protected function checkStorageClass($class) {
        if (!is_a($class, 'Drupal\\Core\\Config\\Entity\\ConfigEntityStorage', TRUE)) {
            throw new ConfigEntityStorageClassException("{$class} is not \\Drupal\\Core\\Config\\Entity\\ConfigEntityStorage or it does not extend it");
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function getPropertiesToExport($id = NULL) {
        // @todo https://www.drupal.org/project/drupal/issues/3113620 Make the
        //   config_export annotation required earlier, remove the possibility of
        //   returning NULL and deprecate the $id argument.
        if (!empty($this->mergedConfigExport)) {
            return $this->mergedConfigExport;
        }
        if (!empty($this->config_export)) {
            // Always add default properties to be exported.
            $this->mergedConfigExport = [
                'uuid' => 'uuid',
                'langcode' => 'langcode',
                'status' => 'status',
                'dependencies' => 'dependencies',
                'third_party_settings' => 'third_party_settings',
                '_core' => '_core',
            ];
            foreach ($this->config_export as $property => $name) {
                if (is_numeric($property)) {
                    $this->mergedConfigExport[$name] = $name;
                }
                else {
                    $this->mergedConfigExport[$property] = $name;
                }
            }
        }
        else {
            return NULL;
        }
        return $this->mergedConfigExport;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getLookupKeys() {
        return $this->lookup_keys;
    }

}