Changing placeholder in file upload map

[ThirVondukr]

Currently with multi file upload file number is always added at the eng (e.g. file.0, file.), and I have an input for a mutation like this:

input FileInput {
  file: Upload!!
}

input MyInput {
  files: [FileInput!]!
}

Which would require me to have keys input.files.{Placeholder Here}.file, which doesn't seem currently possible or simply isn't documented.
It works if I construct that string myself, but then I obviously can't use multi file upload with altair client

Describe the solution you'd like
I think some sort of placeholder could be added, like {} or $ which would be replaced by the file number

Additional context
Example with manually mapping files: