Create a new response Message with code and reason and store
the result message in msg.
Free with free.
When reason is null, the default reason for code will be used.
When request is not null, the relevant headers will be copied to the new response message.
| msg |
a location for the new Message |
| code |
the status code |
| reason |
the status reason or |
| request |
the request that triggered the response or |
|
a Result. |