private static RetryRule retryRule(RetryConfig<HttpResponse> retryConfig) {
        if (retryConfig.needsContentInRule()) {
            return retryConfig.fromRetryRuleWithContent();
        } else {
            final RetryRule rule = retryConfig.retryRule();
            assert rule != null;
            return rule;
        }
    }
Creates a new instance that decorates the specified {@link HttpClient}.
core/src/main/java/com/linecorp/armeria/client/retry/RetryingClient.java