# keeping it simple with just one nested request. no improvement with more added here.
      my $options =
          [
            {
              content => 'GET /gmail/v1/users/real_address@gmail.com/messages/165eb111fcf21503',
              'Content-type' => 'application/http',   # internal server error when set to 'application/json'
            },
          ];

  my $path = 'https://www.googleapis.com/batch/gmail/v1';

  # this is the call to Moo Google's lower level api_query function.
  my $res = $s->_gapi->api_query( {
      httpMethod => 'POST',
      path => $path,
      options => $options,
  });
  print Dumper $res;

# then, over in Moo::Google we do some Mojolicious stuff with our api_query call

   # build the transactor (this function is in Moo::Google
   # $headers was created earlier and contains bearer token
   # $headers->{content-type} = 'mixed/multipart';   # tried this and many other content types with no improvement
   my $tx = $self->ua->build_tx(
         uc $http_method =>$path => $headers => multipart => $options);

    my $res = $self->ua->start($tx)->res;
   return $res;