Typescript 中是否有可能的抽象嵌套类？

Question

我正在尝试使用嵌套抽象生成器 class 制作抽象 class，但是在编写此代码段时，我发现 IDE 开始指出这一点：

找不到名称“抽象”。 ts (2304) [6, 32]

这是我到目前为止写的代码：

export abstract class Quiz {
    protected id: number = 0;
    protected type: string = "";
    protected required_lvl: number = 0;

    protected static Builder = abstract class {
        protected id: number = 0;
        protected type: string = "";
        protected required_lvl: number = 0;

        public setId(id: number) {
            this.id = id;

            return this;
        }

        public setType(type: string) {
            this.type = type;

            return this;
        }

        public setRequiredLvl(required_lvl: number) {
            this.required_lvl = required_lvl;

            return this;
        }

        public abstract build(): Quiz;
    }

    protected constructor(id: number, type: string, required_lvl: number) {
        this.id = id;
        this.type = type;
        this.required_lvl = required_lvl;
    }

    public getId() {
        return this.id;
    }

    public getType() {
        return this.type;
    }

    public getRequiredLvl() {
        return this.required_lvl;
    }
}