static NullSpan& instance() {

    static NullSpan* instance = new NullSpan();

    return *instance;

  }

  void setOperation(absl::string_view) override {}

  void setTag(absl::string_view, absl::string_view) override {}

  void log(SystemTime, const std::string&) override {}

  void finishSpan() override {}

  void injectContext(Tracing::TraceContext&, const UpstreamContext&) override {}

  void setBaggage(absl::string_view, absl::string_view) override {}

  std::string getBaggage(absl::string_view) override { return EMPTY_STRING; }

  std::string getSpanId() const override { return EMPTY_STRING; }

  std::string getTraceId() const override { return EMPTY_STRING; }

  SpanPtr spawnChild(const Config&, const std::string&, SystemTime) override {

    return SpanPtr{new NullSpan()};

  }

  void setSampled(bool) override {}

  bool useLocalDecision() const override { return false; }