Prior to this commit, the Jackson 2.x encoders, in case of encoding a
stream of data, would first release the `ByteArrayBuilder` and then the
`JsonGenerator`. This order is inconsistent with the single value
variant (see `o.s.h.codec.json.AbstractJackson2Encoder#encodeValue`) and
invalid since the `JsonGenerator` uses internally the
`ByteArrayBuilder`.
In case of a CSV Encoder, the codec can buffer data to write the column
names of the CSV file. Writing an empty Flux with this Encoder would not
fail but still log a NullPointerException ignored by the reactive
pipeline.
This commit fixes the order and avoid such issues at runtime.
Fixes gh-30493
d50b51e312