src/vs/editor/common/config/editorOptions.ts/EditorEnumOption/constructor
class EditorEnumOption:	constructor(id: K, name: PossibleKeyName<T>, defaultValue: V, defaultStringValue: string, allowedValues: T[], convert: (value: T) => V, schema: IConfigurationPropertySchema | undefined = undefined) {
		if (typeof schema !== 'undefined') {
			schema.type = 'string';
			schema.enum = allowedValues;
			schema.default = defaultStringValue;
		}
		super(id, name, defaultValue, schema);
		this._allowedValues = allowedValues;
		this._convert = convert;
	}