Shopify file create with GraphQL

shopifyFileCreate.graphql

mutation fileCreate($files: [FileCreateInput!]!) {
  fileCreate(files: $files) {
    files {
      alt
      createdAt
      fileErrors{
          code
          details
          message
      }
      fileStatus
      preview{
          status
          image{
              altText
              url
              id
              width
              height
          }
      }
    }
    userErrors {
      field
      message
    }
  }
}

variables.json

{
  "files": [
    {
      "alt": "",
      "contentType": "IMAGE",
      "originalSource": "https://via.placeholder.com/600/FF0000/FFFFFF"
    }
  ]
}