V14 Upload AcceptedFileTypes Excel (*.xls)

Hi, I could not get the AcceptedFileTypes defined for files ending to “.xls” within the Upload-Component of Vaadin14.
*.xlsx is easy.
I tried this content-types:

  • application/vnd.ms-excel (official)
  • application/msexcel
  • application/x-msexcel
  • application/x-ms-excel
  • application/x-excel
  • application/x-dos_ms_excel
  • application/xls
  • application/x-xls