Attach an email as an item attachment, which includes another attachment

Question

I have been developing an email client using Angular and Microsoft Graph. I am struggling to do an item attachment which has another attachment (let's say a single text file).

I have already went through the Microsoft Graph documentation and the "https://stackoverflow.com/questions/46528376/send-new-message-that-includes-a-different-message-from-users-inbox-as-attachme/46954993#46954993" question. Both the resources describe how to perform an item attachment operation.

In my case, I get an error when I try to attach an item that itself contains an attachment (i.e. a text file).

Here is my approach:

onAttachToNewMail() {
if (this.selectedItems && this.selectedItems.length > 0) {
  const itemAttachments: ItemAttachment[] = this.selectedItems.map(value => {
    const item = <EventMessage>value.data;
    const attachment: ItemAttachment = {
      name: item.subject,
      item: value.data
    };
    attachment.item['@odata.type'] = item.meetingMessageType ? 'microsoft.graph.eventMessage' : 'microsoft.graph.message';
    return attachment;
  });
  this.attachToNewMail.emit(itemAttachments);
}

The error message:

The property attachments does not exist on type Microsoft.OutlookServices.Message. Make sure to only use property names that are defined by the type or mark the type as open type.

How can I fix this problem? Please let me know a solution or workaround to achieve this.