http Client Customizer
var httpClientCustomizer: ERROR CLASS: Symbol not found for HttpClientConfig<ERROR CLASS: Symbol not found for OkHttpConfig>.() -> Unit?
Optional global hook letting platform code customize the OkHttp engine before DefaultHttpClient builds its client (e.g. tutorial apps installing permissive SSL on outdated JDKs, or production apps wiring a corporate proxy / custom truststore). Applied before any caller-supplied config so callers can still override.