[META] Breaking changes in 3.0

[reta]

This is a meta issue which lists down all breaking changes in OpenSearch 3.0

Major updates:

• Upgrade to Lucene 10 - PR
• JDK21 as minimum supported Java runtime - Meta Issue
• Remove all deprecated non-inclusive terms from API
  • Remove deprecated terms from Java API
  • Remove deprecated terms from REST API and cluster settings
• Fix split Java package problem (phase 0)
• Permanently turn-off Security Manager (JSM)

Breaking behavior in 3.0+:

• Add ThreadContextPermission for stashAndMergeHeaders and stashWithOrigin #15039
• Add ThreadContextPermission for markAsSystemContext and allow core to perform the method #15016
• Migrate client transports to Apache HttpClient / Core 5.x #4459
• [BUG] Indexing a document through the bulk api bypasses the 512 byte _id size limit #6595
• [BUG] OpenSearch app is not able to pick up empty node.roles= environment variable to run as coordinating node. #3412 (Treat Setting value with empty array string as empty array #10625)
• Ensure Jackson default maximums introduced in 2.16.0 do not conflict with OpenSearch settings #11811 - content limits in XContent / Jackson
• Introduce index.query.max_nested_depth. fix #3268 #11670
• Fix interchanged formats of total_indexing_buffer_in_bytes and total_indexing_buffer #17070

Removed code in 3.0+

• Cleanup deprecated thread pool settings [REMOVE] Cleanup deprecated thread pool settings #2595
• Replace 'whitelist' terminology in Java API Replace "blacklist/whitelist" terminology in Java APIs #1683
• Removed deprecated methods from JodaCompatibleZonedDateTime [Remove] Remove deprecated methods from JodaCompatibleZonedDateTime which are called by scripts #3346
• List of deprecated code removal in 3.0 #2773
• Remove mmap.extensions setting #9392
• remove the code marked for deprecation (https://github.com/search?q=repo%3Aopensearch-project%2FOpenSearch+%22%40Deprecated%22&type=code by @dbwiddis)
• Remove COMPAT locale provider Issue PR
• [Feature Request] Remove transport-nio plugin #16887

Newly deprecated code in 3.0+

• Deprecate CamelCase PathHierarchy tokenizer name #10894

Misc

• Rename Class ending with Plugin to Module under modules dir Rename Class ending with Plugin to Module under modules dir  #4042
• [Discuss] Changed default settings for 3.0 #17170

[reta]

@saratvemulapalli fyi, meta for 3.0 breaking changes, thanks!

[saratvemulapalli]

@CEHENKLE could you help add this to 3.0 roadmap?

[CEHENKLE]

Done.

[saratvemulapalli]

Looks like this is getting stale.
@andrross /@reta do you think we can use Changelog for this ?

[reta]

@andrross /@reta do you think we can use Changelog for this ?

We probably would have to, but what are other breaking changes to mention? I think @nknize is doing some large refactorings but so far I think it was non breaking.

[andrross]

I did some searching and couldn't find any open issues, but we have deprecation warning about blocking direct access to system indices. @reta is implementing the block for direct access to system indices something we should track for 3.0?

This came up in discussion in #7778.

[reta]

@andrross I think we should track it, thanks!

[andrross]

Created issue #7936 and added to the list here. Thanks!