< Consume:
* - Message offset (or offset for error
* if \c err!=0 if applicable).
* - dr_msg_cb:
* Message offset assigned by broker.
* If \c produce.offset.report is set then
* each message will have this field set,
* otherwise only the last message in
* each produced internal batch will
* have this field set, otherwise 0.
< Consume: * - Message offset (or offset for error * if \c err!=0 if applicable). * - dr_msg_cb: * Message offset assigned by broker. * If \c produce.offset.report is set then * each message will have this field set, * otherwise only the last message in * each produced internal batch will * have this field set, otherwise 0.