Previously, wiki documentation wrongly instructed readers to use the vm_payload tag instead of the payload tag, which made it impossible to set payloads via the API by using the documentation. File injection was also absent.
This made it impossible to setting payloads through the REST API. Documentation has been updated to instruct readers to use the payload tag, and vdsm has been updated so that file injection is added to vm (this was included in VDSM 4.9.1-12). A vm_payload is now found in the database when the payload is set through the REST API.