How to pass URL parameters to NW Gateway Class/Method?

Hi,

This is the pattern of the URL that I would like to use for my getEntitySet:

http://...<Project_SRV.>/TradingContractSet?WERKS=1126

My hope is to constrain the list of trading contract HEADERS to those that have ITEMS from plant 1126.

My stumbling block is how to get a handle to the value of the "WERKS" parameter in the URL.  In the sample URL above, my application code needs to get the value "1126".

I have tried running cl_wd_runtime_services=>get_url_parameters, but this WebDynpro class does not seem to work from within an Gateway ABAP class.

I am able to import FILTER type URL parameters, but that is an overly complex solution.  Additionally, my HEADER entityType does not include WERKS (because WERKS exists at the items level), and I don't want to add the WERKS attribute to the HEADER just for the sake of importing a variable.

I do not see a coding solution for how to do a simple read of a URI parameter from with a NetWeaver Gateway ABAP Class Method.

Any help would be very appreciated!

Regards,

Kevin