Fix ordering of releasing resources in JSON Encoder

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

spring-web/src/main/java/org/springframework/http/codec/json/AbstractJackson2Encoder.java

@@ -205,8 +205,8 @@ public abstract class AbstractJackson2Encoder extends Jackson2CodecSupport imple
 						.doOnNext(dataBuffer -> Hints.touchDataBuffer(dataBuffer, hintsToUse, logger))
 						.doAfterTerminate(() -> {
 							try {
-								byteBuilder.release();
 								generator.close();
+								byteBuilder.release();
 							}
 							catch (IOException ex) {
 								logger.error("Could not close Encoder resources", ex);