ToStringHelper toStringHelper() {
        return MoreObjects
                .toStringHelper(this)
                .omitNullValues()
                .add("retryRule", retryRule)
                .add("retryRuleWithContent", retryRuleWithContent)
                .add("maxTotalAttempts", maxTotalAttempts)
                .add("responseTimeoutMillisForEachAttempt", responseTimeoutMillisForEachAttempt)
                .add("maxContentLength", maxContentLength);
    }
Returns a newly-created {@link RetryConfig} from this {@link RetryConfigBuilder}'s values.
core/src/main/java/com/linecorp/armeria/client/retry/RetryConfigBuilder.java