Header object that is defined on all responses sent from the server.
| JSON representation | 
|---|
{
  "responseTimestamp": {
    object ( | 
            
| Fields | |
|---|---|
responseTimestamp | 
              
                 
 REQUIRED: Timestamp of this response. The receiver must verify that this timestamp is ± 60s of 'now', and reject the response if it is not.  |