Function kvp_to_json_setup 

pub(crate) fn kvp_to_json_setup(params: &[KeyValuePair]) -> FieldValue

Convert draft-11 KVP list to JSON for setup messages.

The three Setup Parameters Section 8.3.2 defines, and no more. There is deliberately no authorization_token here: draft-11 numbers that parameter 0x01 in the version-specific namespace only, where 0x01 among Setup Parameters is PATH, and Section 8.2.1 says outright that “since Setup parameters use a separate namespace, it is impossible for these parameters to appear in Setup messages”. Draft-12 Section 8.3.2.4 is where the token joins this list.