@Override
    public void handle(SnsUnknownMessage message) {
    }
Does nothing by default. Users can override to process but it's not recommended to handle this message
type (instead upgrade to a version of the SDK that have first class support for the message type).

@param message Message object.
aws-java-sdk-sns/src/main/java/com/amazonaws/services/sns/message/DefaultSnsMessageHandler.java