Why doesn't Mediastore.Files work for pdf files on the emulator?

Question

Android

Kind!

I want to get a list of all pdf files on the device in the pdf viewer application.

I do it with this code:

private fun getPdf() {
        val projection = arrayOf(
                MediaStore.Files.FileColumns._ID,
                MediaStore.Files.FileColumns.MIME_TYPE,
                MediaStore.Files.FileColumns.DATE_ADDED,
                MediaStore.Files.FileColumns.DATE_MODIFIED,
                MediaStore.Files.FileColumns.DISPLAY_NAME,
                MediaStore.Files.FileColumns.TITLE,
                MediaStore.Files.FileColumns.SIZE)

        val mimeType = MimeTypeMap.getSingleton().getMimeTypeFromExtension("pdf")
        val whereClause = MediaStore.Files.FileColumns.MIME_TYPE + " IN ('" + mimeType + "')"
        val orderBy = MediaStore.Files.FileColumns.SIZE + " DESC"
        val cursor: Cursor? = contentResolver.query(MediaStore.Files.getContentUri("external"),
                projection,
                whereClause,
                null,
                orderBy)

        val idCol = cursor!!.getColumnIndexOrThrow(MediaStore.Files.FileColumns._ID)
        val mimeCol = cursor.getColumnIndexOrThrow(MediaStore.Files.FileColumns.MIME_TYPE)
        val addedCol = cursor.getColumnIndexOrThrow(MediaStore.Files.FileColumns.DATE_ADDED)
        val modifiedCol = cursor.getColumnIndexOrThrow(MediaStore.Files.FileColumns.DATE_MODIFIED)
        val nameCol = cursor.getColumnIndexOrThrow(MediaStore.Files.FileColumns.DISPLAY_NAME)
        val titleCol = cursor.getColumnIndexOrThrow(MediaStore.Files.FileColumns.TITLE)
        val sizeCol = cursor.getColumnIndexOrThrow(MediaStore.Files.FileColumns.SIZE)

        if (cursor.moveToFirst()) {
            do {

                val fileUri: Uri = Uri.withAppendedPath(MediaStore.Files.getContentUri("external"), cursor.getString(idCol))
                val mimeType = cursor.getString(mimeCol)
                val dateAdded = cursor.getLong(addedCol)
                val dateModified = cursor.getLong(modifiedCol)
                val nameFile = cursor.getString(nameCol)

                if (nameFile!=null) {

                    mPdfFiles.add(PdfFile(nameFile,fileUri))
                    mPdfAdapter.notifyDataSetChanged()

                }

            } while (cursor.moveToNext())
        }
    }

On real devices, it shows downloaded pdf files, but on the emulator it is empty.
On the emulator, it finds only media files - jpg, png, etc. Pdf does not see.

What can be done?