code: public static <I extends Request, O extends Response, L>
      Function<Service<I, O>, StructuredLoggingService<I, O, L>> newDecorator(
              Producer<byte[], L> producer, String topic,
              StructuredLogBuilder<L> logBuilder) {
          return newDecorator(producer, topic, logBuilder, null);
      }
docs: Creates a decorator which provides {@link StructuredLoggingService} with defaulting key to null.
  
  @param producer a kafka {@link Producer} producer which is used to send logs to Kafka
  @param topic a name of topic which is used to send logs
  @param logBuilder an instance of {@link StructuredLogBuilder} which is used to construct a log entry
  @param <I> the {@link Request} type
  @param <O> the {@link Response} type
  @param <L> the type of the structured log representation
  
  @return a service decorator which adds structured logging support integrated to Kafka