Hi, I am trying to write the apex rest outbound program for below apex inbound rest service. Can you please help me on writing the outbound apex rest service. Thanks..

Apex inbound service:

@RestResource(urlMapping='/RestServiceContactCreation/*')

global class RestServiceContactCreation{
    global class ContactRequestDetails{
        webservice String contactLastName;
    }
    
    global class ContactResponseDetails{
        webservice String contactLastName;
        webservice String contactCreationStatus;
    }
    
    global static ContactResponseDetails insertContactDetails(ContactRequestDetails contRequest){
        ContactResponseDetails contResp = new ContactResponseDetails();
            Contact contactObject = new Contact();
            contactObject.LastName = contRequest.contactLastName;
            try
            {
                insert contactObject;
                contResp.contactCreationStatus = 'Contact is created successfully....!!!!! Contact Id: ' +contactObject.Id;
                return contResp;
                }
            catch(Exception ex){
                String errorMessage = 'Error occurred' +ex.getMessage();
                contResp.contactCreationStatus = errorMessage;
                return contResp;
            }
    }
    
    @HttpPost    
    global static ContactResponseDetails createContact(ContactRequestDetails req){
        ContactResponseDetails res = insertContactDetails(req);
        return res;
    }
}

Apex rest outbound:

public class ContactCreationRestservice_Outbound{

    public String response{get;set;}
    
    public class ContactRequestDetails{
        String contactLastName;
    }
    
    public PageReference CreateContact() {
        ContactRequestDetails contReq = new ContactRequestDetails();
        //find access token using Auth 2.0 
        String Access_Token='access token';

        Httprequest req=new httprequest();
        String domainName= '<domainName>';
        String endPointURL='https://domainName-dev-ed.my.salesforce.com/services/apexrest/RestServiceContactCreation/';
        req.setendpoint(endPointURL);
        req.setHeader('Content-Type', 'application/xml; charset=utf-8');
        req.setBody('<?xml version="1.0" encoding="UTF-8" ?><request><name>'+contactLastName+'</name></request>');
        req.setmethod('POST');
        
        req.setHeader('Authorization','Authorization: Bearer '+Access_Token);
        Http http = new Http();
        HTTPResponse res = http.send(req);
        response=res.getbody();
        System.debug('****************res.getStatusCode();'+res.getStatusCode());
        System.debug('****************res.getbody();'+res.getbody());
        return null;
    }
}