post
https://sandbox-api.viantinc.com/{basePath}/creative/save
Allows updating or creating specific types of creatives. Currently Banner creatives and CustomTag (HTML/JS) creatives can be updated, and only CustomTag creatives can be created.
When adding a new creative, id must be null, and the fields campaignId, creativeType, and creativeSubType must be provided. As of this writing only the HTML/JS based CustomTag banners can be created, so the caller must set:
"creativeType": "banner"
and
"creativeSubtype": "htmlTag",