public String getReleaseLabel() {
        return this.releaseLabel;
    }
<p>
The Amazon EMR release label, which determines the version of open-source application packages installed on the
cluster. Release labels are in the form <code>emr-x.x.x</code>, where x.x.x is an Amazon EMR release version such
as <code>emr-5.14.0</code>. For more information about Amazon EMR release versions and included application
versions and features, see <a
href="https://docs.aws.amazon.com/emr/latest/ReleaseGuide/">https://docs.aws.amazon.
com/emr/latest/ReleaseGuide/</a>. The release label applies only to Amazon EMR releases version 4.0 and later.
Earlier versions use <code>AmiVersion</code>.
</p>

@return The Amazon EMR release label, which determines the version of open-source application packages installed
        on the cluster. Release labels are in the form <code>emr-x.x.x</code>, where x.x.x is an Amazon EMR
        release version such as <code>emr-5.14.0</code>. For more information about Amazon EMR release versions
        and included application versions and features, see <a
        href="https://docs.aws.amazon.com/emr/latest/ReleaseGuide/"
        >https://docs.aws.amazon.com/emr/latest/ReleaseGuide/</a>. The release label applies only to Amazon EMR
        releases version 4.0 and later. Earlier versions use <code>AmiVersion</code>.
aws-java-sdk-emr/src/main/java/com/amazonaws/services/elasticmapreduce/model/Cluster.java