Spring unable to decode aggregated JSON content

[filipovskid]

Affects: Spring Framework 6.0.5+

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Issue

Spring fails to decode a JSON payload whose content has been aggregated and represented by at least 2 DataBuffer components, causing the error below to be thrown. This happens only when we have a HttpObjectAggregator in the Netty ChannelPipeline and the content is transformed to a Flux publisher, regardless of whether we block or not when retrieving the data.

com.fasterxml.jackson.core.JsonParseException: Still have 1940 undecoded bytes, should not call 'feedInput'

Even though this is a specific case where we are "bypassing" the reactive nature of WebClient, and I can workaround the issue, I see this as a bug. Please let me know if I am misusing the client and Spring is not supposed to support this use-case.

How to reproduce the issue

Sample Spring Boot project with a data-source application that serves the data and a data-client application where the issue occurs while reading the data To reproduce this issue start both applications and invoke the /get-data-objects endpoint on the client application.

Minimal code

WebClient configuration.

HttpClient httpClient = HttpClient.create()
     .doOnChannelInit((observer, channel, remoteAddress) -> channel.pipeline()
         .addAfter(NettyPipeline.HttpCodec, NettyPipeline.HttpAggregator, new HttpObjectAggregator(1048576)));

ReactorClientHttpConnector connector = new ReactorClientHttpConnector(httpClient );
WebClient webClient = WebClient.builder().baseUrl(BASE_URL)
        .clientConnector(connector)
        .build();

Endpoint invocation.

webClient.get()
     .uri(uriBuilder -> uriBuilder.path("/data").build())
     .retrieve()
     .bodyToFlux(Object.class)
     .collectList()
     .block();

Debugging

I suspect the issue was introduced with the changes to org.springframework.http.codec.json.Jackson2Tokenizer in #29943.