Why External File Field is marked as indexed in solr admin SCHEMA page?

We have following external file field type and field: ** ** In solr official documentation is it mentioned that : *"*The ExternalFileField type makes it possible to specify the values for a field in a file outside the Solr index. *External fields are not searchable. They can be used only for

Best field definition which is only use for filter query.

Below is the sample document *{"filedA": 1,"filedB": "","filedC": "Sher","filedD":