public String getSourceUpdateToken() {
        return this.sourceUpdateToken;
    }
<p>
The update token of the Amazon Web Services managed rule group that your own rule group is copied from. To
determine the update token for the managed rule group, call <a href=
"https://docs.aws.amazon.com/network-firewall/latest/APIReference/API_DescribeRuleGroup.html#networkfirewall-DescribeRuleGroup-response-UpdateToken"
>DescribeRuleGroup</a>.
</p>

@return The update token of the Amazon Web Services managed rule group that your own rule group is copied from.
        To determine the update token for the managed rule group, call <a href=
        "https://docs.aws.amazon.com/network-firewall/latest/APIReference/API_DescribeRuleGroup.html#networkfirewall-DescribeRuleGroup-response-UpdateToken"
        >DescribeRuleGroup</a>.
aws-java-sdk-networkfirewall/src/main/java/com/amazonaws/services/networkfirewall/model/SourceMetadata.java