Check for mTheRealServiceManager nullptr in getInterfaceDescriptor

    void enableAddServiceCache(bool value) { mEnableAddServiceCache = value; }

    // for legacy ABI

    const String16& getInterfaceDescriptor() const override {

        if (mTheRealServiceManager == nullptr) return mNullInterfaceDescriptor;

        return mTheRealServiceManager->getInterfaceDescriptor();

    }

private:

    // Empty descriptor in case there is no mTheRealServiceManager. We need an

    // object to return a String& reference and there is only expected to be a

    // single BackendUnifiedServiceManager per-process, so this is a member

    // variable.

    const String16 mNullInterfaceDescriptor;

    bool mEnableAddServiceCache = true;

    std::shared_ptr<BinderCacheWithInvalidation> mCacheForGetService;

    sp<os::IServiceManager> mTheRealServiceManager;