It used to work on IRIS 2019.. Now I don't remember what version of 2019. I think it was 2019.1.1 but can't bet on it.

Can you please paste the openapi spec for that ?

Another factor which I forgot to mention was that the Path was working past 2 years with the openapi spec I had, it only stopped working on the latest 2020 version.

There are couple of options to do this.

1. You can extend your class &JSON.Adaptor, it will do it for you with inbuilt logicaldtodisplay methods

2. Create another request class and do your transformations

3. Before calling the json convert to stream methods, transform the object's field with a ZDT.