class Net::IMAP::SASL::OAuthAuthenticator

def initial_client_response

formatted response.
The {RFC7628 ยง3.1}[https://www.rfc-editor.org/rfc/rfc7628#section-3.1] 
def initial_client_response
  kv_pairs = {
    host: host, port: port, mthd: mthd, path: path, post: post, qs: qs,
    auth: authorization, # authorization is implemented by subclasses
  }.compact
  [gs2_header, *kv_pairs.map {|kv| kv.join("=") }, "\1"].join("\1")
end