writeContentType method
Sets the content type of the response to 'application/x-yaml'.
This method modifies the headers of the response to indicate that the content
type is 'application/x-yaml' with UTF-8 character encoding.
response is the HTTP response object whose headers will be modified.
Implementation
@override
void writeContentType(Response response) {
response.headers.set('Content-Type', 'application/x-yaml; charset=utf-8');
}