Odata - date functions does't accept date string as a parameter

Date functions year, month, day, hour, minute and second doesn't accept date string(DateTimeOffset) as a parameter.

Reference service which supports OData V4:
ULR: http://services.odata.org/V4/Northwind/Northwind.svc/Employees/?$filter=month(2001-01-01T00:01:01.01Z) eq EmployeeID
Result: Employee with ID 1

URL: http://localhost:8080/odata4/olingo_basic/Source/SimpleDataTable/?$filter=month(2001-01-01T00:01:01.01Z) eq intkey
Result: {"error": {"code": null, "message": "TEIID30069 The function 'MONTH' has more than one possible signature." }}
Expected result: Entity with intkey 1