Investigate whether example code handles file validation properly

After the GraphQL 4.2 security release at https://www.drupal.org/project/graphql/releases/8.x-4.2 the file validation code was changed to fix an invalid file reference during validation. It appears that the example https://github.com/drupal-graphql/graphql-examples/blob/master/src/Plugin/GraphQL/Mutations/FileUpload.php for GraphQL 3.x uses a different logic and is not vulnerable, but please double check that.

Thanks!