DataBufferUtils#join may release a DataBuffer more than necessary

[rstoyanchev]

This is based on investigation under reactor/reactor-netty#1374.

In DataBufferUtils#join we use a custom List to collect buffers and check the total buffered size. When a buffer is added that hits the limit, an error is raised but this causes a double release of the current buffer because Reactor's MonoCollect discards both the item that was passed to the add method and all items in the list. That leads to a double decrease of the refCount when it should be decremented only once.

[zhou-hao]

Will 5.2.13 fix this problem?

[bclozel]

@zhou-hao it was fixed in 5.2.12, see the linked issue #26061