ODataFilterLanguage - should be commented "implements OData V2" #14
Description
There are several versions of ODATA specified.
It seems the class ODataFilterLanguage is implementing "OData V2".
(https://www.odata.org/documentation/odata-version-2-0/overview/)
a future nice-to-have :
ODataFilterLanguageV4 - Implementing Odata V4
http://docs.oasis-open.org/odata/odata/v4.0/errata03/os/complete/abnf/odata-abnf-construction-rules.txt
recognising datetime, datetimeoffnet or guid is now a matter of pattern matching instead of type declaration