extensions/configuration-editing/src/settingsDocumentHelper.ts/SettingsDocument/provideLanguageCompletionItems
class SettingsDocument:	private async provideLanguageCompletionItems(location: Location, position: vscode.Position): Promise<vscode.CompletionItem[]> {
		if (location.path.length === 1 && this.isCompletingPropertyValue(location, position)) {
			const range = this.getReplaceRange(location, position);
			const languages = await vscode.languages.getLanguages();
			return [
				this.newSimpleCompletionItem(JSON.stringify('${activeEditorLanguage}'), range, vscode.l10n.t("Use the language of the currently active text editor if any")),
				...languages.map(l => this.newSimpleCompletionItem(JSON.stringify(l), range))
			];
		}
		return [];
	}