OpenIntegrations/docs/en/examples/HTTPClient/SetJsonBody.txt

    URL = "http://localhost:2424";
    URL = URL + "/post";

    RandomArray = New Array;
    RandomArray.Add("A");
    RandomArray.Add("B");
    RandomArray.Add("C");

    Data = New Structure("Field1,Field2,Field3", 10, "Text", RandomArray);

    Result = OPI_HTTPRequests.NewRequest()
        .Initialize(URL)
        .SetJsonBody(Data) // <---
        .ProcessRequest("POST")
        .ReturnResponseAsJSONObject();