static <T extends Response> RetryRuleWithContent<T> onStatusClass(Iterable<HttpStatusClass> statusClasses,
                                                                      Backoff backoff) {
        return RetryRuleWithContent.<T>builder().onStatusClass(statusClasses).thenBackoff(backoff);
    }
Returns a newly created {@link RetryRuleWithContent} that will retry with the specified {@link Backoff}
if the class of the response status is the specified {@link HttpStatusClass}es.
core/src/main/java/com/linecorp/armeria/client/retry/RetryRuleWithContent.java