Input validation based on Swagger definitions

Hi,

OpenWhisk is a very interesting project and I'm particularly fond of the fact that you decided to utilize Swagger/OpenAPI for API definitions.

However, I went and included a swagger model definition for my request body and noticed that I could make requests that do not conform to the definition without receiving a validation error.

This feature is currently supported by projects such as `swaggerize-express` and I think it is a luxury many developers have grown accustomed to.

Do you have any plans to add support for input validation based on swagger definitions?

No files, tests, or entry points are named. Start by locating OpenWhisk's API request handling and its Swagger/OpenAPI definitions, then determine the validation scope and expected error behavior; done means nonconforming request bodies are rejected consistently.

Written by the indexing model from the issue text.