Unable to set a parameter of type file as optional

[MakarandNsd]

I am not sure if no one needed this before, but I have a use case where the file type parameter is optional, but the code below returns error before validating whether the field is required.

runtime/middleware/parameter.go

Lines 206 to 213 in 3f9800f

	if p.parameter.Type == "file" {
	file, header, ffErr := request.FormFile(p.parameter.Name)
	if ffErr != nil {
	return errors.NewParseError(p.Name, p.parameter.In, "", ffErr)
	}
	target.Set(reflect.ValueOf(runtime.File{Data: file, Header: header}))
	return nil
	}

I can throw in an additional if condition to check if the file is optional and return nil. Please let me know if that works.

[casualjim]

yes please send a PR

[MakarandNsd]

@casualjim , can you please review the pr

[MakarandNsd]

added test cases at #248
@casualjim