JSON API response has empty path when creating an entity

I could be wrong, but setting the path like that I think overwrites the pathauto flag. The return value documentation around these methods is messy, but it passes through from \Drupal\pathauto\AliasStorageHelper::save(), which kinda matches the path item values, but also not fully (there is no source, for example). Maybe we should set the values explicitly, with $entity->get('path')->alias = $result['alias'] and so on?

Updated the MR to reset the path field computed value instead.

Any feedback welcome.

Summary

After Pathauto generates or updates an alias, the entity's in-memory path field still returns NULL or the old alias value, causing JSON:API (and other serializers) to return stale/empty path data in responses.

Problem

Drupal's path field on content entities is a computed field — its value is lazily loaded from the database and then cached in memory for the lifetime of the entity object. When Pathauto generates a new alias during entity->save(), the alias is written to the database but the entity's computed path field still holds the previously cached value. Any code that reads $entity->path->alias after save (e.g. JSON:API serializing the entity in a POST/PATCH response) gets NULL or the old alias instead of the freshly generated one.

Changes

• PathautoFieldItemList.php: Added a resetComputedValue() method that clears the internal item list and resets the valueComputed flag, forcing the field to re-read from the database on next access.
• PathautoGenerator.php: After createEntityAlias() returns a non-null result (meaning an alias was created or updated), resetComputedValue() is called on the entity's path field so the in-memory representation stays in sync.
• PathautoFieldItemListTest.php (new): Kernel test with two scenarios — testResetComputedValueRefreshesAlias() verifies that after an external alias change, calling resetComputedValue() causes the field to return the updated alias; testPathFieldUpdatedAfterAliasGeneration() verifies that after a node title change and save, the path field automatically reflects the new alias without manual intervention.