Using the actual definition in your project you can create schemas from the actual messages in your service - (Schema Inference)
This brief tutorial will walk you through the schema inference function.
We'll start out by creating a new project, and adding a REST service, without an initial WADL file.
After sending the request, we can then use the responses to build our schema.
When a schema has been inferred it is available in the Schema tab in the response window:
The schema can also be added to the service interface and become part of your service definition.