Upload ticket attachment

I am developing an application for flutter and I use splynx api in it. But I had a problem with downloading attachments, according to the documentation https://splynx.docs.apiary.io/#reference/support/ticket-attachments/create-a-ticket-attachment, I pass in the body {files: [file var]} but response {“attachments”: []}
What do I need to convey in the body?

Hello,

please take a look on my example:

You should pass files like:

files[0]: files var
files[1]: second files var
etc