Investigate Upgrade to Jackson 3

[christophstrobl]

https://github.com/FasterXML/jackson/wiki/Jackson-Release-3.0

Related to: spring-projects/spring-data-commons#3292
Due to the amount of breaking changes the upgrade will have a broader impact.

[sothawo]

Did a first step (have a branch in my fork):

I had to change the dependencies and imports. Some adjustments where methods that have been renamed (or better the old ones had been deprecated). So far this works, BUT:

I hand a customized ObjectMapper into the JacksonJsonpMapper that is passed into the RestClient from Elasticsearch (the one ES uses by default discards null values, but sending null values to ES is a valid use case). And the JacksonJsonpMapper of course expect a com.fasterxml.jackson.databind.ObjectMapper.

I will need some more investigation how to address that.

[sothawo]

Looking at https://central.sonatype.com/artifact/co.elastic.clients/elasticsearch-java, the Elasticsearch client 9 references Jackson 2.18.3.

[sothawo]

ok, as Jackson changed the coordinates and package names, it is possible to use a version 2 ObjectMapper for the Elasticsearch client and version 3 for Spring Data Elasticsearch.

Not sure if this is a good idea, and what consequences this might have for users.

[mp911de]

For the time being, we support Jackson 2 side by side with Jackson 3 where possible (e.g. by introducing a Jackson 3-based converter/reader variant) favoring Jackson 3 over Jackson 2 where applicable.

I assume that we will have to support this arrangement until the broader ecosystem has fully migrated to Jackson 3.