Forwarding of the media features in Contact header field (method OPTIONS)

Hello,

We faced following issue when tested RCS services on VoLTE application: before starting group chat the application sends OPTIONS method with its media features attached as header parameters to the Contact. P-CSCF removes those header parameter from forwarded message. I haven't found out any hint regarding use of the media features in the ACLI Guide and forced P-CSCF to keep them whit sip-manipulation applied  and that resolved the problem. Does anybody know which parameter is responsible for saving this information in forwarded non-REGISTER requests ?  Mentioned features are bolded in example shown below.

Contact: <sip:+8113301002212@ims.prc.xxx.mac;transport=tcp;gr=urn:uuid:5667A21D1-B13C-3AD4-6144-54343434D290>;