Why SAP BO BIP RWS does not delete the data provider?

[valerjans]

With SAP BusinessObjects BI Platform 4.2 Support Pack 8 (Version: 14.2.8.3426)

BI Platform Restful Web Service (RWS) does not delete the data provider.

For example, on the DELETE dataprovider request (see Deleting a Data Provider - SAP Help Portal)

with the path:

${#Project#RWS}/raylight/v1/documents/${#Project#DOC}/dataproviders/DP0

RWS gives response:

{"success": { "message": "The resource of type \"Data provider\" with identifier \"DP0\" has not been modified.", "id": "DP0" }}

And on following PUT document request (with no body, see Updating the State of a Document - SAP Help Portal)

with the path:

${#Project#RWS}/raylight/v1/documents/${#Project#DOC}

RWS says that Document "has not been modified".

Also GET document requests shows that the document state is not changed to "Modified" -

after DELETE dataprovider and after PUT document (with no body) the document State still is "Original".

So, how to know, why RWS says "has not been modified", when should be modified (deleted)?

[valerjans]

Possibly related problem:
Why SAP BO BIP RWS does not update the query specification? | SAP Community