PdfDocumentSource allows you to enumerate the supported export formats for a document using the SupportedExportProviders property. The property returns a collection of ExportProvider classes that contain information about the supported formats, and can be used to create the corresponding export filter by using the NewExporter method of ExportProvider class.
Different document types support different sets of export formats, therefore enumerating and creating the export filters via SupportedExportProviders yields the correct results.