public static Function<? super RpcClient, LoggingRpcClient> newDecorator() {
        return builder().newDecorator();
    }
Returns a new {@link RpcClient} decorator that logs {@link Request}s and {@link Response}s at
{@link LogLevel#DEBUG} for success, {@link LogLevel#WARN} for failure.
See {@link LoggingRpcClientBuilder} for more information on the default settings.
core/src/main/java/com/linecorp/armeria/client/logging/LoggingRpcClient.java