To override the Content-type in your clients, use the HTTP Accept Header, append  the .xml suffix or  ?format=xml
        
        HTTP + XML
         The following are sample HTTP requests and responses. 
            The placeholders shown need to be replaced with actual values.
POST /admin/techstacks/{TechnologyStackId}/lock HTTP/1.1 
Host: techstacks.io 
Accept: application/xml
Content-Type: application/xml
Content-Length: length
<LockTechStack xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/TechStacks.ServiceModel">
  <IsLocked>false</IsLocked>
  <TechnologyStackId>0</TechnologyStackId>
</LockTechStack>
 
HTTP/1.1 200 OK
Content-Type: application/xml
Content-Length: length
<LockStackResponse xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/TechStacks.ServiceModel" />