Insert nested XLM nodes if node doesn't exist using Groovy/JavaScript

Question

Below is the XML I am working with

<Root>
    <Employee>
        <EmployeeNumber>10105950</EmployeeNumber>
        <LastName>Myers Jr</LastName>
        <FirstName>Ezell</FirstName>
        <MiddleName/>
        <JobTitle>Tech Shield Strapper</JobTitle>
        <Manager>N</Manager>
        <ManagerID>50501273</ManagerID>
        <BusinessEmail>[email protected]</BusinessEmail>
        <Location>TX06</Location>
        <CostCenter>10200011</CostCenter>
        <HomeLocationCode>TX06 10200011</HomeLocationCode>
        <cust_HomeLocationCode>
            <cust_LocationCode>30</cust_LocationCode>
        </cust_HomeLocationCode>
        <Username>myers10105950</Username>
        <CostCenterName>JASPER OSB Finishing Techshield</CostCenterName>
        <WorkContract>A2</WorkContract>
        <HireDate>11/14/2002</HireDate>
        <PreferredLanguage>1706</PreferredLanguage>
        <PreferredName>Ezell</PreferredName>
    </Employee>
    <Employee>
        <EmployeeNumber>10105951</EmployeeNumber>
        <LastName>Bean</LastName>
        <FirstName>David</FirstName>
        <MiddleName>A</MiddleName>
        <JobTitle>Sr. FP&amp;A Analyst</JobTitle>
        <Manager>N</Manager>
        <ManagerID>10129003</ManagerID>
        <BusinessEmail>[email protected]</BusinessEmail>
        <Location>TX06</Location>
        <CostCenter>11000152</CostCenter>
        <HomeLocationCode>TX06 11000152</HomeLocationCode>
        <Username>beanda</Username>
        <CostCenterName>OSB Finance</CostCenterName>
        <WorkContract>A2</WorkContract>
        <HireDate>07/05/1994</HireDate>
        <PreferredLanguage>1706</PreferredLanguage>
        <PreferredName>David</PreferredName>
    </Employee>
</Root>

I need help writing a groovy script or javascript to evaluate the XML. If <cust_HomeLocationCode> and its contents exist, then skip, else insert the node with <cust_LocationCode> value equaling '1'.

So far I have been able to add just the <cust_HomeLocationCode> node using below code

import com.sap.gateway.ip.core.customdev.util.Message;
import java.util.HashMap;
import groovy.xml.XmlUtil;
import groovy.util.*;

def Message processData(Message message) {
    def body = message.getBody(java.lang.String);
    def root = new XmlParser().parseText(body)
    root.each { Employee ->
        Employee.appendNode("cust_HomeLocationCode", "newfield")
    }
    message.setBody(XmlUtil.serialize(root));
    return message;
}