public String getEngineVersion() {
        return this.engineVersion;
    }
<p>
The upgraded version of the cache engine to be run on the cache nodes.
</p>
<p>
<b>Important:</b> You can upgrade to a newer engine version (see <a
href="https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/SelectEngine.html#VersionManagement">Selecting
a Cache Engine and Version</a>), but you cannot downgrade to an earlier engine version. If you want to use an
earlier engine version, you must delete the existing cluster and create it anew with the earlier engine version.
</p>

@return The upgraded version of the cache engine to be run on the cache nodes.</p>
        <p>
        <b>Important:</b> You can upgrade to a newer engine version (see <a
        href="https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/SelectEngine.html#VersionManagement"
        >Selecting a Cache Engine and Version</a>), but you cannot downgrade to an earlier engine version. If you
        want to use an earlier engine version, you must delete the existing cluster and create it anew with the
        earlier engine version.
aws-java-sdk-elasticache/src/main/java/com/amazonaws/services/elasticache/model/ModifyCacheClusterRequest.java