Shan Huang

Parameters with no example value

3

When a parameter was documented without a example value -- like `since` in **List All Gists** from [Gist Fox API example](https://github.com/apiaryio/api-blueprint/blob/master/examples/Gist%20Fox%20API.md#list-all-gists-get) -- , aglio generated document gave `since` empty string...

solve the problem in #360

These streams are created for single task. `final` them to make it clear and safer.