========================
<vmext:VmVimObjectRef>
<vmext:VimServerRef href="xx.xx.xx.xx/api/admin/extension/vimServer/xxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" id="urn:vcloud:vimserver:xxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" type="application/vnd.vmware.admin.vmwvirtualcenter+xml" name=""/>
<vmext:MoRef>vm-53</vmext:MoRef>
<vmext:VimObjectType>VIRTUAL_MACHINE</vmext:VimObjectType>
</vmext:VmVimObjectRef>
========================
This is a known bug in versions between 10.4.2.1 and 10.5.1.1.
The issue has been fixed in the code starting from vCloud Director version 10.5.2 and in subsequent releases.
The expected output will be as below:
==================
<vmext:VimServerRef href="https://xx.xx.xx.xx/api/admin/extension/vimServer/xxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" id="urn:vcloud:vimserver:xxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" type="application/vnd.vmware.admin.vmwvirtualcenter+xml" name="vCenter"/>
<vmext:MoRef>vm-33</vmext:MoRef>
====================