## 2025-04-28 Version 3.0.0 Release Notes

## [3.0.0]
### Breaking Changes
- Upgrade to Lucene 10.1.0 - PR ([#16366](https://github.com/opensearch-project/OpenSearch/pull/16366))
- JDK21 as minimum supported Java runtime ([#10745](https://github.com/opensearch-project/OpenSearch/issues/10745))
- Remove deprecated terms from Java API ([#5214](https://github.com/opensearch-project/OpenSearch/issues/5214))
- JPMS Support (Eliminate top level split packages ) Phase-0 only ([#8110](https://github.com/opensearch-project/OpenSearch/issues/8110))
- Add ThreadContextPermission for stashAndMergeHeaders and stashWithOrigin ([#15039](https://github.com/opensearch-project/OpenSearch/pull/15039))
- Add ThreadContextPermission for markAsSystemContext and allow core to perform the method ([#15016](https://github.com/opensearch-project/OpenSearch/pull/15016))
- Migrate client transports to Apache HttpClient / Core 5.x ([#4459](https://github.com/opensearch-project/OpenSearch/pull/4459))
- Validation changes on the Bulk Index API like enforcing 512 byte _id size limit ([#6595](https://github.com/opensearch-project/OpenSearch/issues/6595))
- Ability to use the node as coordinating node by passing node.roles as empty array ([#3412](https://github.com/opensearch-project/OpenSearch/issues/3412))
- Treat Setting value with empty array string as empty array ([#10625](https://github.com/opensearch-project/OpenSearch/pull/10625))
- Ensure Jackson default maximums introduced in 2.16.0 do not conflict with OpenSearch settings ([#11811](https://github.com/opensearch-project/OpenSearch/pull/11811))
- Setting a maximum depth for nested queries ([#11670](https://github.com/opensearch-project/OpenSearch/pull/11670))
- Fix interchanged formats of total_indexing_buffer_in_bytes and total_indexing_buffer ([#17070](https://github.com/opensearch-project/OpenSearch/pull/17070))
- Cleanup deprecated thread pool settings ([#2595](https://github.com/opensearch-project/OpenSearch/issues/2595))
- Replace "blacklist/whitelist" terminology in Java APIs ([#1683](https://github.com/opensearch-project/OpenSearch/issues/1683))
- Remove deprecated methods from JodaCompatibleZonedDateTime which are called by scripts ([#3346](https://github.com/opensearch-project/OpenSearch/pull/3346))
- List of deprecated code removal in 3.0- partially done ([#2773](https://github.com/opensearch-project/OpenSearch/issues/2773))
- Remove mmap.extensions setting ([#9392](https://github.com/opensearch-project/OpenSearch/pull/9392))
- Remove COMPAT locale provider ([#13988](https://github.com/opensearch-project/OpenSearch/pull/13988))
- Remove transport-nio plugin ([#16887](https://github.com/opensearch-project/OpenSearch/issues/16887))
- Deprecate CamelCase PathHierarchy tokenizer name ([#10894](https://github.com/opensearch-project/OpenSearch/pull/10894))
- Rename Class ending with Plugin to Module under modules dir ([#4042](https://github.com/opensearch-project/OpenSearch/pull/4042))
- Remove deprecated `batch_size` parameter from `_bulk` ([#14283](https://github.com/opensearch-project/OpenSearch/issues/14283))
- Unset discovery nodes for every transport node actions request ([#17682](https://github.com/opensearch-project/OpenSearch/pull/17682))
- Added cluster:monitor/shards permission for _cat/shards action ([#13966](https://github.com/opensearch-project/OpenSearch/pull/13966))

### Added
- Support for HTTP/2 (server-side) ([#3847](https://github.com/opensearch-project/OpenSearch/pull/3847))
- Allow mmap to use new JDK-19 preview APIs in Apache Lucene 9.4+ ([#5151](https://github.com/opensearch-project/OpenSearch/pull/5151))
- Add events correlation engine plugin ([#6854](https://github.com/opensearch-project/OpenSearch/issues/6854))
- Implement on behalf of token passing for extensions ([#8679](https://github.com/opensearch-project/OpenSearch/pull/8679), [#10664](https://github.com/opensearch-project/OpenSearch/pull/10664))
- Provide service accounts tokens to extensions ([#9618](https://github.com/opensearch-project/OpenSearch/pull/9618))
- GHA to verify checklist items completion in PR descriptions ([#10800](https://github.com/opensearch-project/OpenSearch/pull/10800))
- [WLM] Add WLM support for search scroll API ([#16981](https://github.com/opensearch-project/OpenSearch/pull/16981))
- Views, simplify data access and manipulation by providing a virtual layer over one or more indices ([#11957](https://github.com/opensearch-project/OpenSearch/pull/11957))
- Add systemd configurations to strengthen OS core security ([#17107](https://github.com/opensearch-project/OpenSearch/pull/17107))
- Added pull-based Ingestion (APIs, for ingestion source, a Kafka plugin, and IngestionEngine that pulls data from the ingestion source) ([#16958](https://github.com/opensearch-project/OpenSearch/pull/16958))
- Added ConfigurationUtils to core for the ease of configuration parsing [#17223](https://github.com/opensearch-project/OpenSearch/pull/17223)
- Add cluster and index level settings to limit the total primary shards per node and per index [#17295](https://github.com/opensearch-project/OpenSearch/pull/17295)
- Add execution_hint to cardinality aggregator request ([#17312](https://github.com/opensearch-project/OpenSearch/pull/17312))
- Arrow Flight RPC plugin with Flight server bootstrap logic and client for internode communication ([#16962](https://github.com/opensearch-project/OpenSearch/pull/16962))
- Added offset management for the pull-based Ingestion ([#17354](https://github.com/opensearch-project/OpenSearch/pull/17354))
- Added integ tests for systemd configs ([#17410](https://github.com/opensearch-project/OpenSearch/pull/17410))
- Add filter function for AbstractQueryBuilder, BoolQueryBuilder, ConstantScoreQueryBuilder([#17409](https://github.com/opensearch-project/OpenSearch/pull/17409))
- [Star Tree] [Search] Resolving keyword & numeric bucket aggregation with metric aggregation using star-tree ([#17165](https://github.com/opensearch-project/OpenSearch/pull/17165))
- Added error handling support for the pull-based ingestion ([#17427](https://github.com/opensearch-project/OpenSearch/pull/17427))
- Added Warm index setting and Updated nomenclature to differentiate between hot and warm tiering implementation ([#17490](https://github.com/opensearch-project/OpenSearch/pull/17490))
- Latency and Memory allocation improvements to Multi Term Aggregation queries ([#14993](https://github.com/opensearch-project/OpenSearch/pull/14993))
- Add logic in master service to optimize performance and retain detailed logging for critical cluster operations. ([#14795](https://github.com/opensearch-project/OpenSearch/pull/14795))
- Add Setting to adjust the primary constraint weights ([#16471](https://github.com/opensearch-project/OpenSearch/pull/16471))
- Introduce a setting to disable download of full cluster state from remote on term mismatch([#16798](https://github.com/opensearch-project/OpenSearch/pull/16798/))
- Added ability to retrieve value from DocValues in a flat_object filed([#16802](https://github.com/opensearch-project/OpenSearch/pull/16802))
- Improve performace of NumericTermAggregation by avoiding unnecessary sorting([#17252](https://github.com/opensearch-project/OpenSearch/pull/17252))
- Fix Bug - Handle unsigned long in sorting order assertion of LongHashSet ([#17207](https://github.com/opensearch-project/OpenSearch/pull/17207))
- Implemented computation of segment replication stats at shard level ([#17055](https://github.com/opensearch-project/OpenSearch/pull/17055))
- [Rule Based Auto-tagging] Add in-memory attribute value store ([#17342](https://github.com/opensearch-project/OpenSearch/pull/17342))
- Change priority for scheduling reroute during timeout([#16445](https://github.com/opensearch-project/OpenSearch/pull/16445))
- [Rule Based Auto-tagging] Add rule schema for auto tagging ([#17238](https://github.com/opensearch-project/OpenSearch/pull/17238))
- Renaming the node role search to warm ([#17573](https://github.com/opensearch-project/OpenSearch/pull/17573))
- Introduce a new search node role to hold search only shards ([#17620](https://github.com/opensearch-project/OpenSearch/pull/17620))
- Fix systemd integTest on deb regarding path ownership check ([#17641](https://github.com/opensearch-project/OpenSearch/pull/17641))
- Add dfs transformation function in XContentMapValues ([#17612](https://github.com/opensearch-project/OpenSearch/pull/17612))
- Add tracking for long-running SearchTask post cancellation ([#17726](https://github.com/opensearch-project/OpenSearch/pull/17726))
- Added Kinesis support as a plugin for the pull-based ingestion ([#17615](https://github.com/opensearch-project/OpenSearch/pull/17615))
- Add FilterFieldType for developers who want to wrap MappedFieldType ([#17627](https://github.com/opensearch-project/OpenSearch/pull/17627))
- [Rule Based Auto-tagging] Add in-memory rule processing service ([#17365](https://github.com/opensearch-project/OpenSearch/pull/17365))
- [Security Manager Replacement] Create initial Java Agent to intercept Socket::connect calls ([#17724](https://github.com/opensearch-project/OpenSearch/pull/17724))
- Faster `terms_query` with already sorted terms ([#17714](https://github.com/opensearch-project/OpenSearch/pull/17714))
- Add ingestion management APIs for pause, resume and get ingestion state ([#17631](https://github.com/opensearch-project/OpenSearch/pull/17631))
- [Security Manager Replacement] Enhance Java Agent to intercept System::exit ([#17746](https://github.com/opensearch-project/OpenSearch/pull/17746))
- [Security Manager Replacement] Add a policy parser for Java agent security policies ([#17753](https://github.com/opensearch-project/OpenSearch/pull/17753))
- [Security Manager Replacement] Implement File Interceptor and add integration tests ([#17760](https://github.com/opensearch-project/OpenSearch/pull/17760))
- [Security Manager Replacement] Enhance Java Agent to intercept Runtime::halt ([#17757](https://github.com/opensearch-project/OpenSearch/pull/17757))
- [Security Manager Replacement] Phase off SecurityManager usage in favor of Java Agent ([#17861](https://github.com/opensearch-project/OpenSearch/pull/17861))
- Support AutoExpand for SearchReplica ([#17741](https://github.com/opensearch-project/OpenSearch/pull/17741))
- Add TLS enabled SecureNetty4GrpcServerTransport ([#17796](https://github.com/opensearch-project/OpenSearch/pull/17796))
- Implement fixed interval refresh task scheduling ([#17777](https://github.com/opensearch-project/OpenSearch/pull/17777))
- [Tiered caching] Create a single cache manager for all the disk caches. ([#17513](https://github.com/opensearch-project/OpenSearch/pull/17513))
- Add GRPC DocumentService and Bulk endpoint ([#17727](https://github.com/opensearch-project/OpenSearch/pull/17727))
- Added scale to zero (`search_only` mode) support for OpenSearch reader writer separation ([#17299](https://github.com/opensearch-project/OpenSearch/pull/17299)
- [Star Tree] [Search] Resolving numeric range aggregation with metric aggregation using star-tree ([#17273](https://github.com/opensearch-project/OpenSearch/pull/17273))
- Added Search Only strict routing setting ([#17803](https://github.com/opensearch-project/OpenSearch/pull/17803))
- Disable the index API for ingestion engine ([#17768](https://github.com/opensearch-project/OpenSearch/pull/17768))
- Add SearchService and Search GRPC endpoint ([#17830](https://github.com/opensearch-project/OpenSearch/pull/17830))
- Add update and delete support in pull-based ingestion ([#17822](https://github.com/opensearch-project/OpenSearch/pull/17822))
- Allow maxPollSize and pollTimeout in IngestionSource to be configurable ([#17863](https://github.com/opensearch-project/OpenSearch/pull/17863))
- [Star Tree] [Search] Add query changes to support unsigned-long in star tree ([#17275](https://github.com/opensearch-project/OpenSearch/pull/17275))
- Add `ApproximateMatchAllQuery` that targets match_all queries and approximates sorts ([#17772](https://github.com/opensearch-project/OpenSearch/pull/17772))
- Add TermsQuery support to Search GRPC endpoint ([#17888](https://github.com/opensearch-project/OpenSearch/pull/17888))
- Support sub agg in filter rewrite optimization ([#17447](https://github.com/opensearch-project/OpenSearch/pull/17447)
- Disable scoring of keyword term search by default, fallback logic with new use_similarity:true parameter ([#17889](https://github.com/opensearch-project/OpenSearch/pull/17889))
- Add versioning support in pull-based ingestion ([#17918](https://github.com/opensearch-project/OpenSearch/pull/17918))
- Introducing MergedSegmentWarmerFactory to support the extension of IndexWriter.IndexReaderWarmer ([#17881](https://github.com/opensearch-project/OpenSearch/pull/17881))
- Introduce mapping transformer to allow transform mappings during index create/update or index template create/update ([#17635](https://github.com/opensearch-project/OpenSearch/pull/17635))
- Introduce new dynamic cluster setting to tune maxMergeAtOnce at cluster level ([#17774](https://github.com/opensearch-project/OpenSearch/pull/17774))
- Add multi-threaded writer support in pull-based ingestion ([#17912](https://github.com/opensearch-project/OpenSearch/pull/17912))
- [Star Tree] Support of Boolean Queries in Aggregations ([#17941](https://github.com/opensearch-project/OpenSearch/pull/17941))
- Enabled default throttling for all tasks submitted to cluster manager ([#17711](https://github.com/opensearch-project/OpenSearch/pull/17711))

### Dependencies
- Bump Apache HttpCore5/HttpClient5 dependencies from 5.2.5/5.3.1 to 5.3.1/5.4.1 to support ExtendedSocketOption in HttpAsyncClient ([#16757](https://github.com/opensearch-project/OpenSearch/pull/16757))
- Bumps `jetty` version from 9.4.55.v20240627 to 9.4.57.v20241219 ([#17395](https://github.com/opensearch-project/OpenSearch/pull/17395))
- Switch main/3.x to use JDK21 LTS version ([#17515](https://github.com/opensearch-project/OpenSearch/pull/17515))
- Bump `org.awaitility:awaitility` from 4.2.0 to 4.3.0 ([#17230](https://github.com/opensearch-project/OpenSearch/pull/17230), [#17439](https://github.com/opensearch-project/OpenSearch/pull/17439))
- Bump `dnsjava:dnsjava` from 3.6.2 to 3.6.3 ([#17231](https://github.com/opensearch-project/OpenSearch/pull/17231))
- Bump `com.google.code.gson:gson` from 2.11.0 to 2.13.0 ([#17229](https://github.com/opensearch-project/OpenSearch/pull/17229), [#17668](https://github.com/opensearch-project/OpenSearch/pull/17668), [#17921](https://github.com/opensearch-project/OpenSearch/pull/17921)), [#17926](https://github.com/opensearch-project/OpenSearch/pull/17926))
- Bump `org.jruby.joni:joni` from 2.2.1 to 2.2.6 ([#17136](https://github.com/opensearch-project/OpenSearch/pull/17136), [#17608](https://github.com/opensearch-project/OpenSearch/pull/17608), [#17732](https://github.com/opensearch-project/OpenSearch/pull/17732))
- Bump `org.apache.ant:ant` from 1.10.14 to 1.10.15 ([#17288](https://github.com/opensearch-project/OpenSearch/pull/17288))
- Bump `reactor_netty` from 1.1.26 to 1.2.3 ([#17322](https://github.com/opensearch-project/OpenSearch/pull/17322), [#17322](https://github.com/opensearch-project/OpenSearch/pull/17322), [#17377](https://github.com/opensearch-project/OpenSearch/pull/17377))
- Bump `me.champeau.gradle.japicmp` from 0.4.5 to 0.4.6 ([#17375](https://github.com/opensearch-project/OpenSearch/pull/17375))
- Bump `com.google.api.grpc:proto-google-common-protos` from 2.37.1 to 2.54.1 ([#17379](https://github.com/opensearch-project/OpenSearch/pull/17379), [#17733](https://github.com/opensearch-project/OpenSearch/pull/17733))
- Bump `net.minidev:json-smart` from 2.5.1 to 2.5.2 ([#17378](https://github.com/opensearch-project/OpenSearch/pull/17378))
- Bump `com.netflix.nebula.ospackage-base` from 11.10.1 to 11.11.2 ([#17374](https://github.com/opensearch-project/OpenSearch/pull/17374), [#17734](https://github.com/opensearch-project/OpenSearch/pull/17734))
- Bump `ch.qos.logback:logback-classic` from 1.5.16 to 1.5.18 ([#17497](https://github.com/opensearch-project/OpenSearch/pull/17497), [#17730](https://github.com/opensearch-project/OpenSearch/pull/17730))
- Bump `software.amazon.awssdk` from 2.20.86 to 2.30.31 ([#17396](https://github.com/opensearch-project/OpenSearch/pull/17396))
- Bump `org.jruby.jcodings:jcodings` from 1.0.61 to 1.0.63 ([#17560](https://github.com/opensearch-project/OpenSearch/pull/17560))
- Bump `com.azure:azure-storage-blob` from 12.28.1 to 12.30.0 ([#17562](https://github.com/opensearch-project/OpenSearch/pull/17562), [#17667](https://github.com/opensearch-project/OpenSearch/pull/17667))
- Bump `com.nimbusds:nimbus-jose-jwt` from 9.41.1 to 10.0.2 ([#17607](https://github.com/opensearch-project/OpenSearch/pull/17607), [#17669](https://github.com/opensearch-project/OpenSearch/pull/17669))
- Bump `com.google.api:api-common` from 1.8.1 to 2.46.1 ([#17604](https://github.com/opensearch-project/OpenSearch/pull/17604))
- Bump `ch.qos.logback:logback-core` from 1.5.16 to 1.5.18 ([#17609](https://github.com/opensearch-project/OpenSearch/pull/17609), [#17809](https://github.com/opensearch-project/OpenSearch/pull/17809))
- Bump `dangoslen/dependabot-changelog-helper` from 3 to 4 ([#17498](https://github.com/opensearch-project/OpenSearch/pull/17498))
- Bump `com.google.api:gax` from 2.35.0 to 2.63.1 ([#17465](https://github.com/opensearch-project/OpenSearch/pull/17465))
- Bump `tj-actions/changed-files` from 46.0.1 to 46.0.5 ([#17666](https://github.com/opensearch-project/OpenSearch/pull/17666), [#17813](https://github.com/opensearch-project/OpenSearch/pull/17813), [#17920](https://github.com/opensearch-project/OpenSearch/pull/17920))
- Bump `com.github.luben:zstd-jni` from 1.5.5-1 to 1.5.6-1 ([#17674](https://github.com/opensearch-project/OpenSearch/pull/17674))
- Bump `lycheeverse/lychee-action` from 2.3.0 to 2.4.0 ([#17731](https://github.com/opensearch-project/OpenSearch/pull/17731))
- Bump `com.nimbusds:oauth2-oidc-sdk` from 11.21 to 11.23.1 ([#17729](https://github.com/opensearch-project/OpenSearch/pull/17729))
- Bump `com.google.api.grpc:proto-google-iam-v1` from 1.33.0 to 1.49.1 ([#17811](https://github.com/opensearch-project/OpenSearch/pull/17811))
- Bump `com.azure:azure-core` from 1.54.1 to 1.55.3 ([#17810](https://github.com/opensearch-project/OpenSearch/pull/17810))
- Bump `org.apache.poi` version from 5.2.5 to 5.4.1 in /plugins/ingest-attachment ([#17887](https://github.com/opensearch-project/OpenSearch/pull/17887))
- Bump `org.opensearch:protobufs` from 0.2.0 to 0.3.0 ([#17888](https://github.com/opensearch-project/OpenSearch/pull/17888))

### Changed
- Changed locale provider from COMPAT to CLDR  ([#14345](https://github.com/opensearch-project/OpenSearch/pull/14345))
- Change http code on create index API with bad input raising NotXContentException from 500 to 400 ([#4773](https://github.com/opensearch-project/OpenSearch/pull/4773))
- Improve summary error message for invalid setting updates ([#4792](https://github.com/opensearch-project/OpenSearch/pull/4792))
- Return 409 Conflict HTTP status instead of 503 on failure to concurrently execute snapshots ([#8986](https://github.com/opensearch-project/OpenSearch/pull/5855))
- Add task completion count in search backpressure stats API ([#10028](https://github.com/opensearch-project/OpenSearch/pull/10028/))
- Breaking change: Do not request "search_pipelines" metrics by default in NodesInfoRequest ([#12497](https://github.com/opensearch-project/OpenSearch/pull/12497))
- Use simpler matching logic for source fields when explicit field names (no wildcards or dot-paths) are specified ([#17160](https://github.com/opensearch-project/OpenSearch/pull/17160))
- Refactor `:libs` module `bootstrap` package to eliminate top level split packages for JPMS support ([#17117](https://github.com/opensearch-project/OpenSearch/pull/17117))
- Refactor the codebase to eliminate top level split packages for JPMS support ([#17153](https://github.com/opensearch-project/OpenSearch/pull/17153)
- Refactor `:server` module `org.apacge.lucene` package to eliminate top level split packages for JPMS support ([#17241](https://github.com/opensearch-project/OpenSearch/pull/17241))
- Stop minimizing automata used for case-insensitive matches ([#17268](https://github.com/opensearch-project/OpenSearch/pull/17268))
- Refactor the `:server` module `org.opensearch.client` to `org.opensearch.transport.client` to eliminate top level split packages for JPMS support ([#17272](https://github.com/opensearch-project/OpenSearch/pull/17272))
- Use Lucene `BM25Similarity` as default since the `LegacyBM25Similarity` is marked as deprecated ([#17306](https://github.com/opensearch-project/OpenSearch/pull/17306))
- Wildcard field index only 3gram of the input data [#17349](https://github.com/opensearch-project/OpenSearch/pull/17349)
- Use BC libraries to parse PEM files, increase key length, allow general use of known cryptographic binary extensions, remove unused BC dependencies ([#17393](https://github.com/opensearch-project/OpenSearch/pull/17393))
- Add optional enum set read / write functionality to stream input / output ([#17556](https://github.com/opensearch-project/OpenSearch/pull/17556))
- Convert transport-reactor-netty4 to use gradle version catalog [#17233](https://github.com/opensearch-project/OpenSearch/pull/17233)
- Increase force merge threads to 1/8th of cores [#17255](https://github.com/opensearch-project/OpenSearch/pull/17255)
- TieredSpilloverCache took-time threshold now guards heap tier as well as disk tier [#17190](https://github.com/opensearch-project/OpenSearch/pull/17190)
- Migrate BC libs to their FIPS counterparts ([#17507](https://github.com/opensearch-project/OpenSearch/pull/17507))
- Increase the floor segment size to 16MB ([#17699](https://github.com/opensearch-project/OpenSearch/pull/17699))
- Unwrap singleton DocValues in global ordinal value source of composite histogram aggregation ([#17740](https://github.com/opensearch-project/OpenSearch/pull/17740))
- Unwrap singleton DocValues in date histogram aggregation. ([#17643](https://github.com/opensearch-project/OpenSearch/pull/17643))
- Introduce 512 byte limit to search and ingest pipeline IDs ([#17786](https://github.com/opensearch-project/OpenSearch/pull/17786))
- Avoid skewed segment replication lag metric ([#17831](https://github.com/opensearch-project/OpenSearch/pull/17831))
- Increase the default segment counter step size when replica promoting ([#17568](https://github.com/opensearch-project/OpenSearch/pull/17568))
- [WLM] Rename QueryGroup to WorkloadGroup ([#17901](https://github.com/opensearch-project/OpenSearch/pull/17901))
- Relaxes jarHell check for optionally extended plugins([#17893](https://github.com/opensearch-project/OpenSearch/pull/17893)))
- Add cluster setting for retry timeout of publish checkpoint tx action ([#17749](https://github.com/opensearch-project/OpenSearch/pull/17749))
- Increase the default maxMergesAtOnce to 30 ([#17774](https://github.com/opensearch-project/OpenSearch/pull/17774))
- Change the default max header size from 8KB to 16KB. ([#18024](https://github.com/opensearch-project/OpenSearch/pull/18024))
- Enable concurrent_segment_search auto mode by default[#17978](https://github.com/opensearch-project/OpenSearch/pull/17978)
- Skip approximation when `track_total_hits` is set to `true` [#18017](https://github.com/opensearch-project/OpenSearch/pull/18017)

### Deprecated

### Removed
- Remove deprecated code to add node name into log pattern of log4j property file ([#4568](https://github.com/opensearch-project/OpenSearch/pull/4568))
- Unused object and import within TransportClusterAllocationExplainAction ([#4639](https://github.com/opensearch-project/OpenSearch/pull/4639))
- Remove LegacyESVersion.V_7_0_* and V_7_1_* Constants ([#2768](https://https://github.com/opensearch-project/OpenSearch/pull/2768))
- Remove LegacyESVersion.V_7_2_ and V_7_3_ Constants ([#4702](https://github.com/opensearch-project/OpenSearch/pull/4702))
- Always auto release the flood stage block ([#4703](https://github.com/opensearch-project/OpenSearch/pull/4703))
- Remove LegacyESVersion.V_7_4_ and V_7_5_ Constants ([#4704](https://github.com/opensearch-project/OpenSearch/pull/4704))
- Remove Legacy Version support from Snapshot/Restore Service ([#4728](https://github.com/opensearch-project/OpenSearch/pull/4728))
- Remove deprecated serialization logic from pipeline aggs ([#4847](https://github.com/opensearch-project/OpenSearch/pull/4847))
- Remove unused private methods ([#4926](https://github.com/opensearch-project/OpenSearch/pull/4926))
- Remove LegacyESVersion.V_7_8_ and V_7_9_ Constants ([#4855](https://github.com/opensearch-project/OpenSearch/pull/4855))
- Remove LegacyESVersion.V_7_6_ and V_7_7_ Constants ([#4837](https://github.com/opensearch-project/OpenSearch/pull/4837))
- Remove LegacyESVersion.V_7_10_ Constants ([#5018](https://github.com/opensearch-project/OpenSearch/pull/5018))
- Remove Version.V_1_ Constants ([#5021](https://github.com/opensearch-project/OpenSearch/pull/5021))
- Remove custom Map, List and Set collection classes ([#6871](https://github.com/opensearch-project/OpenSearch/pull/6871))
- Remove package org.opensearch.action.support.master ([#4856](https://github.com/opensearch-project/OpenSearch/issues/4856))
- Remove deprecated 'gateway' settings used to defer cluster recovery ([#3117](https://github.com/opensearch-project/OpenSearch/issues/3117))
- Remove FeatureFlags.PLUGGABLE_CACHE as the feature is no longer experimental ([#17344](https://github.com/opensearch-project/OpenSearch/pull/17344))
- Remove `FeatureFlags.APPROXIMATE_POINT_RANGE_QUERY_SETTING` since range query approximation is no longer experimental ([#17769](https://github.com/opensearch-project/OpenSearch/pull/17769))

### Fixed
- Fix 'org.apache.hc.core5.http.ParseException: Invalid protocol version' under JDK 16+ ([#4827](https://github.com/opensearch-project/OpenSearch/pull/4827))
- Fix compression support for h2c protocol ([#4944](https://github.com/opensearch-project/OpenSearch/pull/4944))
- Don't over-allocate in HeapBufferedAsyncEntityConsumer in order to consume the response ([#9993](https://github.com/opensearch-project/OpenSearch/pull/9993))
- Add HTTP/2 protocol support to HttpRequest.HttpVersion ([#17248](https://github.com/opensearch-project/OpenSearch/pull/17248))
- Fix missing bucket in terms aggregation with missing value ([#17418](https://github.com/opensearch-project/OpenSearch/pull/17418))
- Fix explain action on query rewrite ([#17286](https://github.com/opensearch-project/OpenSearch/pull/17286))
- Fix visit of inner query for FunctionScoreQueryBuilder ([#16776](https://github.com/opensearch-project/OpenSearch/pull/16776))
- Fix case insensitive and escaped query on wildcard ([#16827](https://github.com/opensearch-project/OpenSearch/pull/16827))
- Fix exists queries on nested flat_object fields throws exception ([#16803](https://github.com/opensearch-project/OpenSearch/pull/16803))
- Add highlighting for wildcard search on `match_only_text` field ([#17101](https://github.com/opensearch-project/OpenSearch/pull/17101))
- Fix illegal argument exception when creating a PIT ([#16781](https://github.com/opensearch-project/OpenSearch/pull/16781))
- Fix NPE in node stats due to QueryGroupTasks ([#17576](https://github.com/opensearch-project/OpenSearch/pull/17576))
- Fix bytes parameter on `_cat/recovery` ([#17598](https://github.com/opensearch-project/OpenSearch/pull/17598))
- Fix slow performance of FeatureFlag checks ([#17611](https://github.com/opensearch-project/OpenSearch/pull/17611))
- Fix shard recovery in pull-based ingestion to avoid skipping messages ([#17868](https://github.com/opensearch-project/OpenSearch/pull/17868)))
- Fix ingest pipeline cannot be executed when retry the failed index requests for update_by_query API and reindex API ([#18003](https://github.com/opensearch-project/OpenSearch/pull/18003))
- With creation of FilterFieldType, we need unwrap all the MappedFieldType before using the instanceof check. ([#17951](https://github.com/opensearch-project/OpenSearch/pull/17951))
