public String getAgentVersion() {
        return this.agentVersion;
    }
<p>
The default OpsWorks Stacks agent version. You have the following options:
</p>
<ul>
<li>
<p>
Auto-update - Set this parameter to <code>LATEST</code>. OpsWorks Stacks automatically installs new agent
versions on the stack's instances as soon as they are available.
</p>
</li>
<li>
<p>
Fixed version - Set this parameter to your preferred agent version. To update the agent version, you must edit
the stack configuration and specify a new version. OpsWorks Stacks installs that version on the stack's
instances.
</p>
</li>
</ul>
<p>
The default setting is <code>LATEST</code>. To specify an agent version, you must use the complete version
number, not the abbreviated number shown on the console. For a list of available agent version numbers, call
<a>DescribeAgentVersions</a>. AgentVersion cannot be set to Chef 12.2.
</p>
<note>
<p>
You can also specify an agent version when you create or update an instance, which overrides the stack's default
setting.
</p>
</note>

@return The default OpsWorks Stacks agent version. You have the following options:</p>
        <ul>
        <li>
        <p>
        Auto-update - Set this parameter to <code>LATEST</code>. OpsWorks Stacks automatically installs new agent
        versions on the stack's instances as soon as they are available.
        </p>
        </li>
        <li>
        <p>
        Fixed version - Set this parameter to your preferred agent version. To update the agent version, you must
        edit the stack configuration and specify a new version. OpsWorks Stacks installs that version on the
        stack's instances.
        </p>
        </li>
        </ul>
        <p>
        The default setting is <code>LATEST</code>. To specify an agent version, you must use the complete
        version number, not the abbreviated number shown on the console. For a list of available agent version
        numbers, call <a>DescribeAgentVersions</a>. AgentVersion cannot be set to Chef 12.2.
        </p>
        <note>
        <p>
        You can also specify an agent version when you create or update an instance, which overrides the stack's
        default setting.
        </p>
aws-java-sdk-opsworks/src/main/java/com/amazonaws/services/opsworks/model/UpdateStackRequest.java