POST $url
POST $url, Header => Value,...
POST $url, $form_ref, Header => Value,...
POST $url, Header => Value,..., Content => $form_ref
POST $url, Header => Value,..., Content => $content

##</code><code>##

my $attributes = { name => "test.txt", parent => { id => 0 }};

$ua->post(ENDPOINT,
   Content_Type => 'form-data',
   Authorization => "Bearer $token",
   Content => [
      attributes => encode_json($attributes),
      file       => [ "test.txt" ],
   ],
);

##</code><code>##

[ undef, "test.txt", Content => $file_contents ]