Convenience function to set the request body of a #SoupMessage. If @content_type is %NULL, the request body must be empty as well.
MIME Content-Type of the body
a #SoupMemoryUse describing how to handle @req_body
a data buffer containing the body of the message request.
See Implementation
Convenience function to set the request body of a #SoupMessage. If @content_type is %NULL, the request body must be empty as well.