test.java

    factory.addServerCustomizers(httpServer -> httpServer.tcpConfiguration(
        tcpServer -> tcpServer.bootstrap(serverBootstrap -> {
              serverBootstrap.config().childGroup().forEach(eventExecutor -> {
                if (SingleThreadEventExecutor.class.isAssignableFrom(eventExecutor.getClass())) {
                  SingleThreadEventExecutor singleThreadEventExecutor = (SingleThreadEventExecutor) eventExecutor;

                  Gauge.builder(SERVER_PENDING_TASK_METRIC, singleThreadEventExecutor::pendingTasks)
                      .description("Pending Tasks")
                      .tag(SERVER_THREAD_NAME, singleThreadEventExecutor.threadProperties().name())
                      .tag(SERVER_THREAD_STATE, singleThreadEventExecutor.threadProperties().state().name())
                      .register(registry);
                }
              });
              return serverBootstrap;
            }
        )));