docs: function(params, cb) {
      var correlationId = _cbt.put(offsetResponse(cb));
      var msg = envelope(off.encode()
                            .correlation(correlationId)
                            .client(_options.clientId)
                            .replica()
                            .topic(params.topic)
                            .partition(params.partition)
                            .timestamp()
                            .maxOffsets()
                            .end());
      sendMsg(msg, correlationId, cb);
    }