HarmonyOS ArkTS语法报错咨询

代码如下：

//callback申明
interface ResultCallBack {
  onResult(result: string): void;
}

class Bulider{
  public static resultCallBack:ResultCallBack;
  public start():void{
  }

  public setResultCallBack(resultCallBack:ResultCallBack):Bulider{
    Bulider.resultCallBack = resultCallBack;
    return this;
  }
}

class PluginInstance {
  private static instance: PluginInstance;
  private constructor(){}
  public static getInstance(): PluginInstance {
    if (!PluginInstance.instance) {
      PluginInstance.instance = new PluginInstance();
    }
    return PluginInstance.instance;
  }

  public start(callBack: ResultCallBack): void {
    if (!callBack) {
      return;
    }
    let bulider: Bulider = new Bulider();
    bulider.setResultCallBack(callBack).start();
    Bulider.resultCallBack.onResult('test callBack')
  }
}

//callback使用
let pluginInstance: PluginInstance = PluginInstance.getInstance();
let resultCallback: ResultCallBack = {
  onResult: (result: string) => {
    console.log(result);
  }
};
pluginInstance.start(resultCallback);
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请问以上代码倒数第六行：

let resultCallback: ResultCallBack = {  
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处报错“Object literal must correspond to some explicitly declared class or interface (arkts-no-untyped-obj-literals) <ArkTSCheck>”，如何解决？