Define complex type in ServiceStack Slagger-UI

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service

API

I'm trying to achieve something like this http://petstore.swagger.wordnik.com/#!/store/placeOrder_post_2 I want to set a complex type as DataType of ServiceStack.ServiceHost.ApiMember attribute as I want to have JSON schema to this field. In the swagger-ui documentation is written:

The specification supports any complex type as long as it is declared in the models section.

but I couldn't find how to do that with ServiceStack.