Allow translation even if no translatable fields are present.

I have a node with no translatable fields but a reference to a custom entity I can edit through inline entity form. The embedded entity has in oposite to the parent node some translatable fields. But I can't translate them because entity translation thinks there is nothing to translate and I get "no translatable fields".

On nodes with translatable fields the language is passed correctly to the embedded child entities and can be translated together with the node fields.