The odd thing is that they are not using three:

    public connectorsEnabled(enabled: boolean): this;
    public connectorsEnabled(): boolean;
    public connectorsEnabled(enabled?: boolean): any {
      if (enabled == null) {
        return this._connectorsEnabled;
      }
      this._connectorsEnabled = enabled;
      return this;
    }

In that way, typescript will use the most specific overload to do type checking, so you'll get an actual boolean when doing connectorsEnabled(); instead of any.