src/vs/workbench/contrib/preferences/browser/settingsTree.ts/createObjectKeySuggester
function createObjectKeySuggester(element: SettingsTreeSettingElement): IObjectKeySuggester {
	const { objectProperties } = element.setting;
	const allStaticKeys = Object.keys(objectProperties ?? {});

	return keys => {
		const existingKeys = new Set(keys);
		const enumOptions: IObjectEnumOption[] = [];

		allStaticKeys.forEach(staticKey => {
			if (!existingKeys.has(staticKey)) {
				enumOptions.push({ value: staticKey, description: objectProperties![staticKey].description });
			}
		});

		return enumOptions.length > 0
			? { type: 'enum', data: enumOptions[0].value, options: enumOptions }
			: undefined;
	};
}