The Json format that should be used for the posted message. The ‘flat’ format presents a single level json object and ‘nested’ is a structured json format.
query-string
string
optional
sets the custom query string of the webservice service. The query string MUST NOT be URL encoded, and MUST NOT contain the query string leading character ’?’, e.g. ‘field1=value1&redirect=https://localhost/callback’ or ‘a,b,c,d’