Thank you for the reference. Is there any plan to support attachments in REST or support OAuth2 in SOAP?

Thank you. Appreciate your help.

Thank you for your prompt response. In this way, to create 10 contacts for a vendor, I have to make 10 POST calls to /contact endpoint instead of 1 call to /vendor endpoint . contactList is a sub list of vendor record. Is it not allowed to create a sub-list while updating a record as mentioned in this document -…

I am trying to create new contact which doesn't exist. So there is no contact id generated yet. This is a use case of creating a sub-list.

No error encountered via UI.