private static BlockingTaskExecutor monitorBlockingTaskExecutor(BlockingTaskExecutor executor,
                                                                    MeterRegistry meterRegistry) {
        new ExecutorServiceMetrics(
                executor.unwrap(),
                "blockingTaskExecutor", "armeria", ImmutableList.of())
                .bindTo(meterRegistry);
        return executor;
    }
Initialized later by {@link Server} via {@link #setServer(Server)}.
core/src/main/java/com/linecorp/armeria/server/DefaultServerConfig.java