I was not able to get the code to work.

Kill parameters

Merge parameters = %request.Data

Set genericRequest = ##class(Core.API.V1.Msg.GenericRequest).%New()

Set genericRequest.urlParameters = parameters

I was not able to get the code to work when my class had property

Property urlParameters As %String [multidimensional];

I was able to get it to work with the following.

Property urlParameters As %Library.ArrayOfDataTypes;  //property in generic request class

In Dispatch:

Set genericRequest.urlParameters = ##class(%Library.ArrayOfDataTypes).%New()

Set propName = $Order(%request.Data(""))

While (propName '= "") {

Set param = %request.Data(propName, 1)

do genericRequest.urlParameters.SetAt(propName, param)

Set propName = $Order(%request.Data(propName))

}