public void setMessageTypes(java.util.Collection<String> messageTypes) {
        if (messageTypes == null) {
            this.messageTypes = null;
            return;
        }

        this.messageTypes = new java.util.ArrayList<String>(messageTypes);
    }
<p>
The type of message. Valid values are TRANSACTIONAL for messages that are critical or time-sensitive and
PROMOTIONAL for messages that aren't critical or time-sensitive.
</p>

@param messageTypes
       The type of message. Valid values are TRANSACTIONAL for messages that are critical or time-sensitive and
       PROMOTIONAL for messages that aren't critical or time-sensitive.
@see MessageType
aws-java-sdk-pinpointsmsvoicev2/src/main/java/com/amazonaws/services/pinpointsmsvoicev2/model/RequestSenderIdRequest.java