src/vs/workbench/services/dialogs/browser/simpleFileDialog.ts/SimpleFileDialog/getScheme
class SimpleFileDialog:	private getScheme(available: readonly string[] | undefined, defaultUri: URI | undefined): string {
		if (available && available.length > 0) {
			if (defaultUri && (available.indexOf(defaultUri.scheme) >= 0)) {
				return defaultUri.scheme;
			}
			return available[0];
		} else if (defaultUri) {
			return defaultUri.scheme;
		}
		return Schemas.file;
	}