@Bean
    public HealthChecker tomcatConnectorHealthChecker(ServletWebServerApplicationContext applicationContext) {
        final Connector connector = getConnector(applicationContext);
        return () -> connector.getState().isAvailable();
    }
Returns a new {@link HealthChecker} that marks the server as unhealthy when Tomcat becomes unavailable.
examples/spring-boot-tomcat/src/main/java/example/springframework/boot/tomcat/HelloConfiguration.java