How to upload Item Attributes via BPA REST API

Summary:

Using BPA Import Rest API to add item to BPA and create Item in PIM. Need to populate Item Attributes

Content (please ensure you mask any confidential information):

Rest API: /fscmRestApi/resources/11.13.18.05/purchaseAgreementImportRequests/{InterfaceHeaderId}/child/lines/{InterfaceLineId}/child/itemAttributes

In the BPA Import FBDI, you're able to populate the item attributes which then appear on the item in PIM upon upload and item creation.

When attempting to complete the same via REST API, you're able to populate the BPA Line attributes, but there's no option to populate the Item Attributes tab.

Version (include the version you are using, if applicable):