We have configured SAP Gateway OData services in SMP 2.3 with Relay server and testing these services in chrome rest client(POSTMAN).
When we call 'GET' method on SMP, It's working fine and able to fetch the csrf token.
But when we try to call 'POST' on SMP, It says '403 forbidden - csrf token validation failed' though we are passing csrf token value properly in headers.
From SMP logs, We found that SMP server is preparing payload and all header values properly before making call to gateway but when request reaches to gateway, CSRF token value gets disappeared, In return GW response gives 'CSRF token validation failed since value is going blank'.
Note that if we test 'GET' and 'POST' method from rest client with SAP gateway server settings both are working fine and we don't see this error.
Also, POST request which is giving this error is passing through Relay server to a SMP proxy connection.
Any help would be appreciated.