sample-process-models/misc/upload-file/upload-file-schema.json

{
  "title": "Text Field",
  "description": "A simple text field that is required, has a default value, sets a placeholder, includes a description. (field name will be 'firstname')",
  "type": "object",
  "required": [
    "file"
  ],
  "properties": {
    "file": {
      "type": "string",
      "title": "First name",
      "format": "data-url"
    }
  }
}