Improve guidance on working with and releasing DataBuffer's [SPR-17409] #21942
Description
Rossen Stoyanchev opened SPR-17409 and commented
In particular focusing on releasing in case of error and cancellation signal scenarios, for code that deals with data buffers directly, i.e. outside of the built-in codecs. This could be custom encocders or decoders, a WebSocketHandler processing DataBuffers, or any other code (e.g. Spring Cloud Gateway) that handles DataBuffer's in a pipeline with operators that might do pre-fetching and queuing like flatMap.
Affects: 5.0.10, 5.1.1
This issue is a sub-task of #21941