Migrate from TopicProcessor

TopicProcessor has been removed since the 3.4+ reactor version and now I'm struggling how is the easiest way to replace it with a new API. I'd like to keep the implementation as reliable as possible, even if the performance will get worst. I don't want to struggle with loss events or an overflowing stream, just keep it stupid simple. I also need to buffer data, so I've used bufferTimeout for that and it worked perfectly with TopicProcessor. How to achieve that with the new API?

I've tried to use Sinks but with a lot of pressure there was an overflow exception and the whole stream was terminated.

Below is my basic implementation before upgrade to Spring Boot 2.4.1.

package com.example.reactorplayground.config;

import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

public class TopicProcessor<T> implements Processor<T> {
    private final reactor.core.publisher.TopicProcessor<T> processor;

    public TopicProcessor() {
        this.processor = reactor.core.publisher.TopicProcessor.share("in-memory-topic-thread", 1);
    }

    @Override
    public Mono<T> add(T event) {
        return Mono.fromCallable(() -> {
            processor.onNext(event);
            return event;
        });
    }

    @Override
    public Flux<T> consumeWith() {
        return processor;
    }
}