Content without uuid are generated on export, but that leads to lots of problems. UUIDs are optional, not mandatory.
Per EntityTypeInterface::getKeys
documentation:
* - uuid: (optional) The name of the property that contains the universally
* unique identifier of the entity, which is used to distinctly identify
* an entity across different systems.
Ignore when the content entity doesn't provide a uuid field definition or uuid returned is empty.
Ignore entity references referencing content with empty uuid or no uuid field definition.
Review patch.
In single export and import forms, entity types not providing a UUID key are not listed.
None.
None.
4.0
Export/Import
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