src/vs/workbench/services/dialogs/browser/fileDialogService.ts/FileDialogService/getFilePickerTypes
class FileDialogService:	private getFilePickerTypes(filters?: FileFilter[]): FilePickerAcceptType[] | undefined {
		return filters?.filter(filter => {
			return !((filter.extensions.length === 1) && ((filter.extensions[0] === '*') || filter.extensions[0] === ''));
		}).map(filter => {
			const accept: Record<string, string[]> = {};
			const extensions = filter.extensions.filter(ext => (ext.indexOf('-') < 0) && (ext.indexOf('*') < 0) && (ext.indexOf('_') < 0));
			accept[getMediaOrTextMime(`fileName.${filter.extensions[0]}`) ?? 'text/plain'] = extensions.map(ext => ext.startsWith('.') ? ext : `.${ext}`);
			return {
				description: filter.name,
				accept
			};
		});
	}