Problem/Motivation
\Drupal\system\Entity\Action::setPlugin() is not actually part of any interface, despite that its docblock uses {@inheritdoc}.
/**
* {@inheritdoc}
*/
public function setPlugin($plugin_id) {
$this->plugin = $plugin_id;
$this->getPluginCollection()->addInstanceId($plugin_id);
}
Proposed resolution
Add this method to ActionConfigEntityInterface
API changes
Because there is a 1-1 relationship between \Drupal\system\Entity\Action and \Drupal\system\ActionConfigEntityInterface this is permissible in 8.x due to the Interfaces within non-experimental, non-test modules not tagged with either @api or @internal section of https://www.drupal.org/core/d8-bc-policy.
However, we should add a change notice.
Release notes snippet
What needs to be done is there should be "setplugin()" method availabe in ActionConfigEntityInterface for mapping 1-1 with
\Drupal\system\Entity\Action.