-callback http_connection_options(State :: term(), Url :: binary()) ->
                                     {ok,
                                      Host :: inet:hostname() | inet:ip_address(),
                                      Port :: inet:port_number(),
                                      Opts :: gun:opts(),
                                      State :: term()} |
                                     not_supported |
                                     {error, term()}.

-callback http_init(Options :: map()) -> {ok, State :: term()} | {error, REason :: term()}.

-callback http_request_options(State :: term(), Method :: method(), Url :: binary(), Path :: binary()) ->
                                  {ok, Path :: binary(), Headers :: [{binary(), binary()}], State :: term()} |
                                  {error, term()}.