t() :: %Attentive.Config{
  api_key: String.t(),
  http_client: module(),
  http_client_opts: any(),
  http_headers: Attentive.http_headers_t(),
  http_host: String.t(),
  http_path: String.t(),
  http_port: pos_integer(),
  http_protocol: String.t(),
  json_codec: module(),
  retry: boolean() | module(),
  retry_opts: Keyword.t()
}