Reference service which supports OData V4:
ULR: http://services.odata.org/V4/Northwind/Northwind.svc/Employees/?$filter=EmployeeID%20eq%20round(4.2)
Result: Employee with ID 4

URL: http://localhost:8080/odata4/olingo_basic/Source/SimpleTableView/?$filter=intkey%20eq%20round(4.2)
Actual result: {"error": {"code": null, "message": "TEIID30558 Error converting parameter number 1 with value \"4,2\" of class java.math.BigDecimal to expected type integer." }}
Expected result: Entity with intkey 4