How to clear the Date of Birth

Hi,

I am wondering how I can make the "Date Of Birth" field empty in SAP Marketing Cloud.

The DOB can be set via

https://{{url}}-api.s4hana.ondemand.com/sap/opu/odata/sap/API_MKT_CONTACT_SRV;v=0004/$batch

with payload (leaving out some of the batch/changeset and irrelevant payload parts to make it readable)

[...]
PATCH ContactOriginData(ContactID='{{ID}}',ContactOrigin='{{ORIGIN}}') HTTP/1.1
[...]

{
    "OriginDataLastChgUTCDateTime" : "{{Timestamp}}",
    "BirthDate":"1965-10-28T00:00:00"
 }

[...]

However, when we try to clear the DOB with this payload:

[...]
PATCH ContactOriginData(ContactID='{{ID}}',ContactOrigin='{{ORIGIN}}') HTTP/1.1
[...]

{
    "OriginDataLastChgUTCDateTime" : "{{Timestamp}}",
    "BirthDate":""
 }

[...]

there is an error:

{"error":{"code":"/IWCOR/CX_DS_EP_PROPERTY_ERROR/005056A509B11ED1BF822D2D0917DA04","message":{"lang":"en","value":"Property 'BirthDate' at offset '82' has invalid value ''"},