Function kvp_to_json_d07_inner 

fn kvp_to_json_d07_inner(
    params: &[KeyValuePair],
    name_fn: fn(u64) -> Option<&'static str>,
    is_varint_fn: fn(u64) -> bool,
) -> FieldValue

Convert draft-07 KVP list to JSON. In draft-07, all values are length-prefixed bytes. For known varint parameters, decode the bytes as a VarInt.