public static TomcatService of(Tomcat tomcat) {
        return new UnmanagedTomcatService(requireNonNull(tomcat, "tomcat"));
    }
Creates a new {@link TomcatService} from an existing {@link Tomcat} instance.
If the specified {@link Tomcat} instance is not configured properly, the returned {@link TomcatService}
may respond with '503 Service Not Available' error.

@return a new {@link TomcatService}, which will not manage the provided {@link Tomcat} instance.
tomcat10/src/main/java/com/linecorp/armeria/server/tomcat/TomcatService.java