Undefined Entities are not indexed

[giraygi]

Describe the bug
If an entity is part of a triple in a particular ontology but not described in any ontology in the service, then it is not indexed

To Reproduce
aco > aco:AudioFile rdfs:subClassOf ebu:MediaResource > ebu:MediaResource is not indexed, despite implicitly being a class

Expected behavior
Those entities should also be indexed.

[SArndt-TIB]

VANN is another example: https://vocab.org/vann/vann-vocab-20100607.rdf
The classes and individuals are not recognized by ols4:

Other than in Protege:

[SArndt-TIB]

I just saw another example on a local ingest - the superclass is not ingested (cannot be displayed in hierarchy, not searchable). Source file is https://gitlab.com/dgarayr/ontorxn/-/raw/prod/OntoRXN.owl

[SArndt-TIB]

chemrof will be another example, there will be some parent classes with LinkML IRIs that do not show up in class hierarchy. cf.