*
 * A good way to signal a failure is with a synthetic HTTP response:
 *
 * ```kotlin
 *   @Throws(IOException::class)
 *   override fun intercept(chain: Interceptor.Chain): Response {
 *     if (myConfig.isInvalid()) {
 *       return Response.Builder()
 *           .request(chain.request())
 *           .protocol(Protocol.HTTP_1_1)
 *           .code(400)
 *           .message("client config invalid")