public void setDownlinkMode(String downlinkMode) {
        this.downlinkMode = downlinkMode;
    }
<p>
Indicates whether to send the downlink message in sequential mode or concurrent mode, or to use only the chosen
gateways from the previous uplink message transmission.
</p>

@param downlinkMode
       Indicates whether to send the downlink message in sequential mode or concurrent mode, or to use only the
       chosen gateways from the previous uplink message transmission.
@see DownlinkMode
aws-java-sdk-iotwireless/src/main/java/com/amazonaws/services/iotwireless/model/ParticipatingGateways.java