public String getEngineVersion() {
        return this.engineVersion;
    }
<p>
The version number of the database engine to which you want to upgrade. Changing this parameter results in an
outage. The change is applied during the next maintenance window unless the <code>ApplyImmediately</code>
parameter is set to true.
</p>
<p>
For a list of valid engine versions, see <a
href="https://docs.aws.amazon.com/neptune/latest/userguide/engine-releases.html">Engine Releases for Amazon
Neptune</a>, or call <a>DescribeDBEngineVersions</a>.
</p>

@return The version number of the database engine to which you want to upgrade. Changing this parameter results
        in an outage. The change is applied during the next maintenance window unless the
        <code>ApplyImmediately</code> parameter is set to true.</p>
        <p>
        For a list of valid engine versions, see <a
        href="https://docs.aws.amazon.com/neptune/latest/userguide/engine-releases.html">Engine Releases for
        Amazon Neptune</a>, or call <a>DescribeDBEngineVersions</a>.
aws-java-sdk-neptune/src/main/java/com/amazonaws/services/neptune/model/ModifyDBClusterRequest.java