Returns whether this entity is being changed as part of an import process.
If you are writing code that responds to a change in this entity (insert, update, delete, presave, etc.), and your code would result in a configuration change (whether related to this configuration entity, another configuration entity, or non-entity configuration) or your code would result in a change to this entity itself, you need to check and see if this entity change is part of an import process, and skip executing your code if that is the case.
For example, \Drupal\node\Entity\NodeType::postSave() adds the default body field to newly created node type configuration entities, which is a configuration change. You would not want this code to run during an import, because imported entities were already given the body field when they were originally created, and the imported configuration includes all of their currently-configured fields. On the other hand, \Drupal\field\Entity\FieldStorageConfig::preSave() and the methods it calls make sure that the storage tables are created or updated for the field storage configuration entity, which is not a configuration change, and it must be done whether due to an import or not. So, the first method should check $entity->isSyncing() and skip executing if it returns TRUE, and the second should not perform this check.
bool TRUE if the configuration entity is being created, updated, or deleted through the import process.
lib/ Drupal/ Core/ Config/ Entity/ ConfigEntityInterface.php, line 94
- Defines a common interface for configuration entities.
public function isSyncing();