public String getOptInType() {
        return this.optInType;
    }
<p>
A value that specifies the type of opt-in request, or undoes an opt-in request. An opt-in request of type
<code>immediate</code> can't be undone.
</p>
<p>
Valid values:
</p>
<ul>
<li>
<p>
<code>immediate</code> - Apply the maintenance action immediately.
</p>
</li>
<li>
<p>
<code>next-maintenance</code> - Apply the maintenance action during the next maintenance window for the resource.
</p>
</li>
<li>
<p>
<code>undo-opt-in</code> - Cancel any existing <code>next-maintenance</code> opt-in requests.
</p>
</li>
</ul>

@return A value that specifies the type of opt-in request, or undoes an opt-in request. An opt-in request of type
        <code>immediate</code> can't be undone.</p>
        <p>
        Valid values:
        </p>
        <ul>
        <li>
        <p>
        <code>immediate</code> - Apply the maintenance action immediately.
        </p>
        </li>
        <li>
        <p>
        <code>next-maintenance</code> - Apply the maintenance action during the next maintenance window for the
        resource.
        </p>
        </li>
        <li>
        <p>
        <code>undo-opt-in</code> - Cancel any existing <code>next-maintenance</code> opt-in requests.
        </p>
        </li>
aws-java-sdk-neptune/src/main/java/com/amazonaws/services/neptune/model/ApplyPendingMaintenanceActionRequest.java