code: public static void storeTracerInfo(ClientRequestContext requestContext) {
  
          // tracer信息放入request 发到服务端
          SofaTraceContext sofaTraceContext = SofaTraceContextHolder.getSofaTraceContext();
          SofaTracerSpan clientSpan = sofaTraceContext.getCurrentSpan();
          RpcInternalContext context = RpcInternalContext.getContext();
          if (clientSpan != null) {
              requestContext.getHeaders().add(RemotingConstants.NEW_RPC_TRACE_NAME,
                  clientSpan.getSofaTracerSpanContext().serializeSpanContext());
          }
          // 客户端发送自己的应用名
          String appName = (String) context.getAttachment(INTERNAL_KEY_APP_NAME);
          if (appName != null) {
              requestContext.getHeaders().add(RemotingConstants.HEAD_APP_NAME, appName);
          }
      }
docs: 存入tracer信息
  
  @param requestContext ClientRequestContext