Non-required parameters are checked for the in-file example

For model validation, the request object composed for in-file example includes the non-required parameter. This ends up with false alarm on the non-required parameter type mismatch. Code fix may be around [here](https://github.com/Azure/oav/blob/d5deab20237e61f754ef26e23b7773eacac31448/lib/validators/modelValidator.ts#L458)

Since there're few cases using in-file example for swagger specs, so make this issue as low priority.

Start in lib/validators/modelValidator.ts around line 458 and trace how requests are composed for in-file examples. Verify how non-required parameters are included and how type mismatches are reported. Done means optional parameters no longer produce false type-mismatch alarms in these examples.

Written by the indexing model from the issue text.