send-queue.js

// Turn our form data into a JSON string
const data ={
  ...
  data: {
    ...
    integrations: [
      {type: 'integrationX' ... },
      {type: 'integrationY' ... }
    ]
  }
};
const jsonString = JSON.stringify(data);

// Our files to upload
const jsonFile = new Blob([jsonString], {type: 'application/vnd.umeakommun.basicuse+json'})
const fileUploadedByUser = document.querySelector('input[name="uploadFile"]');

// Create a form containing our files
var form = new FormData();
form.append('upload1', jsonFile, 'form.json');
form.append('upload2', fileUploadedByUser);

// Send our form to server
axios({
  method: 'POST', 
  url: '/api/v1.0/send',
  data: form,
  config: { 
    headers: {
      'Content-Type': 'multipart/form-data',
      Authorization: 'Bearer ' + userAccessToken
    }
  }
});