public void setUpgradeStep(String upgradeStep) {
        this.upgradeStep = upgradeStep;
    }
<p>
Represents one of 3 steps that an Upgrade or Upgrade Eligibility Check does through:
<ul>
<li>PreUpgradeCheck</li>
<li>Snapshot</li>
<li>Upgrade</li>
</ul>
</p>

@param upgradeStep
       Represents one of 3 steps that an Upgrade or Upgrade Eligibility Check does through:
       <ul>
       <li>PreUpgradeCheck</li>
       <li>Snapshot</li>
       <li>Upgrade</li>
       </ul>
@see UpgradeStep
aws-java-sdk-elasticsearch/src/main/java/com/amazonaws/services/elasticsearch/model/UpgradeStepItem.java