class Workflow

class Workflow extends ConfigEntityBase implements WorkflowInterface, EntityWithPluginCollectionInterface {
    
    /**
     * The Workflow ID.
     *
     * @var string
     */
    protected $id;
    
    /**
     * The workflow label.
     *
     * @var string
     */
    protected $label;
    
    /**
     * The workflow type plugin ID.
     *
     * @see \Drupal\workflows\WorkflowTypeManager
     *
     * @var string
     */
    protected $type;
    
    /**
     * The configuration for the workflow type plugin.
     *
     * @var array
     */
    protected $type_settings = [];
    
    /**
     * The workflow type plugin collection.
     *
     * @var \Drupal\Component\Plugin\LazyPluginCollection
     */
    protected $pluginCollection;
    
    /**
     * {@inheritdoc}
     */
    public function preSave(EntityStorageInterface $storage) {
        $workflow_type = $this->getTypePlugin();
        $missing_states = array_diff($workflow_type->getRequiredStates(), array_keys($this->getTypePlugin()
            ->getStates()));
        if (!empty($missing_states)) {
            throw new RequiredStateMissingException(sprintf("Workflow type '{$workflow_type->label()}' requires states with the ID '%s' in workflow '{$this->id()}'", implode("', '", $missing_states)));
        }
        parent::preSave($storage);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getTypePlugin() {
        return $this->getPluginCollection()
            ->get($this->type);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getPluginCollections() {
        return [
            'type_settings' => $this->getPluginCollection(),
        ];
    }
    
    /**
     * Encapsulates the creation of the workflow's plugin collection.
     *
     * @return \Drupal\Core\Plugin\DefaultSingleLazyPluginCollection
     *   The workflow's plugin collection.
     */
    protected function getPluginCollection() {
        if (!$this->pluginCollection && $this->type) {
            $this->pluginCollection = new DefaultSingleLazyPluginCollection(\Drupal::service('plugin.manager.workflows.type'), $this->type, $this->type_settings);
        }
        return $this->pluginCollection;
    }
    
    /**
     * Loads all workflows of the provided type.
     *
     * @param string $type
     *   The workflow type to load all workflows for.
     *
     * @return static[]
     *   An array of workflow objects of the provided workflow type, indexed by
     *   their IDs.
     *
     *  @see \Drupal\workflows\Annotation\WorkflowType
     */
    public static function loadMultipleByType($type) {
        return self::loadMultiple(\Drupal::entityQuery('workflow')->condition('type', $type)
            ->execute());
    }
    
    /**
     * {@inheritdoc}
     */
    public function status() {
        // In order for a workflow to be usable it must have at least one state.
        return !empty($this->status) && !empty($this->getTypePlugin()
            ->getStates());
    }
    
    /**
     * {@inheritdoc}
     */
    public function onDependencyRemoval(array $dependencies) {
        // Give the parent method and the workflow type plugin a chance to react
        // to removed dependencies and report if either of these two made a change.
        $parent_changed_entity = parent::onDependencyRemoval($dependencies);
        $plugin_changed_entity = $this->getTypePlugin()
            ->onDependencyRemoval($dependencies);
        return $plugin_changed_entity || $parent_changed_entity;
    }

}