Change record status: 
Project: 
Introduced in branch: 
8.x
Description: 

If your ConfigEntity class uses a PluginBag in order to manage its plugins, you now should implement Drupal\Core\Config\Entity\EntityWithPluginBagInterface.
This will provide automatic handling of your plugin's configuration, keeping it in sync when an entity is saved.
If you are storing your plugin's configuration on the entity in a property other than $configuration, you must specify that as follows in your entity class:
protected $pluginConfigKey = 'my_settings';

Impacts: 
Module developers
Updates Done (doc team, etc.)
Online documentation: 
Not done
Theming guide: 
Not done
Module developer documentation: 
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Examples project: 
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Coder Review: 
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Coder Upgrade: 
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Other: 
Other updates done