docs: private void updateFdMetrics() {
      if (osMbean instanceof com.sun.management.UnixOperatingSystemMXBean) {
        final com.sun.management.UnixOperatingSystemMXBean unix =
            (com.sun.management.UnixOperatingSystemMXBean) osMbean;
  
        fdCount.setValue(unix.getOpenFileDescriptorCount());
        fdLimit.setValue(unix.getMaxFileDescriptorCount());
      }
    }