final ToStringHelper toStringHelper() {
        if (retryConfigBuilder == null) {
            return MoreObjects.toStringHelper(this).add("mapping", mapping);
        }
        return retryConfigBuilder.toStringHelper();
    }
Sets the response timeout for each attempt. When requests in {@link AbstractRetryingClient} are made,
corresponding responses are timed out by this value. {@code 0} disables the timeout.

@return {@code this} to support method chaining.

@see <a href="https://armeria.dev/docs/client-retry#per-attempt-timeout">Per-attempt timeout</a>

@deprecated Use {@link RetryConfigBuilder#responseTimeoutForEachAttempt(Duration)} instead.
core/src/main/java/com/linecorp/armeria/client/retry/AbstractRetryingClientBuilder.java