public Builder setStaleIfErrorEnabled(final boolean enabled) {
            this.staleIfErrorEnabled = enabled;
            return this;
        }
Enables or disables the stale-if-error cache directive. If this option
is enabled, cached responses that have become stale due to an error (such
as a server error or a network failure) will be returned instead of
generating a new request. This can help to reduce the load on the origin
server and improve performance.
<p>
By default, the stale-if-error directive is disabled.
</p>

@param enabled a boolean value indicating whether the stale-if-error
               directive should be enabled.
@return this instance.
httpclient5-cache/src/main/java/org/apache/hc/client5/http/impl/cache/CacheConfig.java