How to use the midway-core.MidwayHandlerKey.PLUGIN function in midway-core

// 如果是typescript会加上 dist 或者 src 目录
    this.containerLoader = new ContainerLoader({
      baseDir: this.appDir,
      isTsMode: this.isTsMode
    });
    this.containerLoader.initialize();
    this.applicationContext.registerObject('appDir', this.appDir);
    // 如果没有关闭autoLoad 则进行load
    this.containerLoader.loadDirectory(containerConfig);

    // register handler for container
    this.containerLoader.registerHook(MidwayHandlerKey.CONFIG, (key: string) => {
      return safelyGet(key, this.config);
    });

    this.containerLoader.registerHook(MidwayHandlerKey.PLUGIN, (key: string) => {
      return this.app[key] || this.pluginContext.get(key);
    });

    this.containerLoader.registerHook(MidwayHandlerKey.LOGGER, (key: string) => {
      if (this.app.getLogger) {
        return this.app.getLogger(key);
      }
      return this.options.logger;
    });
  }

registerDecorator() {
    // register handler for container
    this.loader.registerHook(MidwayHandlerKey.CONFIG, key => {
      return this.globalConfig[key];
    });

    this.loader.registerHook(MidwayHandlerKey.PLUGIN, (key, target) => {
      const ctx = target[REQUEST_OBJ_CTX_KEY] || {};
      return ctx[key];
    });

    this.loader.registerHook(MidwayHandlerKey.LOGGER, (key, target) => {
      const ctx = target[REQUEST_OBJ_CTX_KEY] || {};
      return ctx['logger'];
    });
  }