Issue Summary

During import, if a reference attribute is selected as identifier, then the import doesn't create objects, and shows an error on the UI.
Currently, there is no support for reference type identifiers in imports.

Steps to Reproduce

1. Set the import source OTAttr mapped to attr X as identifier
2. Start import for given import source

Expected Results

The import for this case should be supported, and it should not lead to an erro

Actual Results

The import fails with the below error in UI

X error(s) found in source data  

Workaround

The only option is to remove those attributes as identifier.