tWith this model
The following XPaths should be valid because they only refer the join table and don’t require any data from external entities:
[MyConsumer.Local_External/MyConsumer.External]
[NOT(MyConsumer.Local_External/MyConsumer.External)]
[MyConsumer.Local_External/MyConsumer.External = $External]
Upd: same is true for non-persistable entities: their associations with regular entities must be available in XPath and not cause: is not allowed in an XPath constraint, because it starts in an entity that is not persistable