How to upload a File object through getBackendSrv().fetch?

Hi, I’m having trouble to upload a file through Grafana getBackendSrv().

I have a DataSource plugin, where I should upload files from the frontend to it. In order to do this, I set a route at the plugin.json file, routing to the appropriate endpoint of my service.

What happened is that, if I use Grafana’s getBackendSrv() it simply fails to send the FormData object, sending a file=%5Bobject+File%5D content.

Here is a snippet:

async uploadSystem(file: File) {
    const endpoint = Collections['applyManualUpdate'];
    const url = this.route_endpoint + endpoint;
    let formData = new FormData();
    formData.append('file', file);
    return await getBackendSrv()
      .fetch({
        url: url,
        data: formData,
        method: 'post',
        headers: { 'Content-Type': 'multipart/form-data' },
      })
      .toPromise();
    }

Is it not possible to send files through this method at all?