types/serviceendpoints.ps1xml

<?xml version="1.0" encoding="utf-8" ?>
<Types>
   <!--Team.ServiceEndpoint-->
   <Type>
      <Name>Team.ServiceEndpoint</Name>
      <Members>
         <ScriptProperty>
            <Name>createdByUser</Name>
            <GetScriptBlock>$this.createdBy.displayName</GetScriptBlock>
         </ScriptProperty>
      </Members>
   </Type>
</Types>