public void setMessageId(String messageId) {
        this.messageId = messageId;
    }
<p>
The ID to assign to the message. Within each batch sent, each <code>"messageId"</code> must be unique.
</p>

@param messageId
       The ID to assign to the message. Within each batch sent, each <code>"messageId"</code> must be unique.
aws-java-sdk-ioteventsdata/src/main/java/com/amazonaws/services/ioteventsdata/model/Message.java