Since #12241 we have notifications for this when the user navigates away from the viewer, but we do not yet warn when switching documents, which means that if you call e.g. `PDFViewerApplication.open` with a new document (or directly call `BaseViewer.setDocument` when using the viewer components standalone) there won't be any warning about losing form data. This should be addressed.
"2.2",
  "2.3",
];
const KNOWN_GENERATORS = [
  "acrobat distiller",
  "acrobat pdfwriter",
  "adobe livecycle",
  "adobe pdf library",
  "adobe photoshop",
  "ghostscript",
  "tcpdf",
  "cairo",
  "dvipdfm",
  "dvips",
  "pdftex",
  "pdfkit",
  "itext",
  "prince",
  "quarkxpress",
  "mac os x",
  "microsoft",
  "openoffice",
  "oracle",
  "luradocument",
  "pdf-xchange",
  "antenna house",
  "aspose.cells",
  "fpdf",
];
class DefaultExternalServices {