@Override
    public String toString() {
        return this.value;
    }
<p>
The type of EBS volume, standard, gp2, gp3 or io1. See <a href=
"http://docs.aws.amazon.com/elasticsearch-service/latest/developerguide/es-createupdatedomains.html#es-createdomain-configure-ebs"
target="_blank">Configuring EBS-based Storage</a>for more information.
</p>
aws-java-sdk-elasticsearch/src/main/java/com/amazonaws/services/elasticsearch/model/VolumeType.java