URL = "https://bin.openintegrations.dev";
    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)
        .StartMultipartBody(True, "related")
        .AddDataAsRelated(Data, "application/json; charset=UTF-8") // <---
        .ProcessRequest("POST")
        .ReturnResponseAsJSONObject();