Mirrors the trailing portion of #5414 onto
feature/mustang-ppl-integration. The Gradle 9.4.1 wrapper bump (#5406)
and the integTest exclude block for @ignore'd classes (#5407) already
landed on this branch, but the matching cleanup of `CalciteNoPushdownIT`
did not — the @suite still listed four classes that are now build-time
excluded from integTest:

  - CalciteInformationSchemaCommandIT
  - CalciteJsonFunctionsIT
  - CalcitePrometheusDataSourceCommandsIT
  - CalciteShowDataSourcesCommandIT

Leaving them in the suite means the JUnit runner attempts to load each
class, finds it referenced from the suite, and registers a descriptor —
which (combined with the class-level @ignore) reproduces the same
TestEventReporterAsListener.started cast that the integTest exclude was
meant to avoid. Dropping the entries here keeps the no-pushdown suite
consistent with the exclude block: a class excluded at the build layer
must not also appear in any @Suite.SuiteClasses list.

No new tests are introduced or removed — the four classes are already
@ignore'd and have been since they were written. This change is purely
about keeping the no-pushdown suite metadata aligned with the exclusion
pattern carried over from main.

Signed-off-by: Kai Huang <ahkcs@amazon.com>

Bring the analytics-engine catch-up PR up to current upstream/main by
resolving conflicts introduced by 4 main commits since 2026-04-30:

- opensearch-project#5419 (LENGTH/REGEXP_REPLACE/DATE_TRUNC unified function spec)
- opensearch-project#5408 (datetime type normalization)
- opensearch-project#5414 (Gradle wrapper bump + @ignore exclusion)
- opensearch-project#5399 (FGAC-scoped SQL cursor continuation)

Resolutions:

api/spec/* (LanguageSpec, UnifiedFunctionSpec, UnifiedPplSpec,
UnifiedSqlSpec): took main. Main is a strict superset — adds
postAnalysisRules and preCompilationRules extension points, the new
FunctionSpecBuilder DSL, SCALAR category for length/regexp_replace/
date_trunc, the DatetimeExtension on PPL spec, and the CoreExtension
wiring on SQL spec. PR's RELEVANCE category is preserved unchanged.

api/UnifiedQueryPlanner.java, api/compiler/UnifiedQueryCompiler.java:
took main. Both adopt the new postAnalysisRules / preCompilationRules
hooks introduced in opensearch-project#5408 / opensearch-project#5419.

core/executor/QueryService.java: composed both sides — kept HEAD's
CalciteClassLoaderHelper.withCalciteClassLoader wrapper around main's
StageErrorHandler stage tracking. Same pattern as the original PR
resolution; both improvements are orthogonal.

plugin/SQLPlugin.java: kept HEAD imports for ExplainResponse and
QueryType (referenced by createSqlAnalyticsRouter, which only exists
on the feature branch).

plugin/transport/TransportPPLQueryAction.java: kept HEAD's
queryPlanExecutor parameter alongside main's extensionsHolder
parameter, since both are referenced in the constructor body.

legacy/plugin/RestSqlAction.java: took HEAD. The 3-way merge produced
a duplicated handleException/getRawErrorCode block; HEAD already
contained both the delegateToV2Engine refactor and the ErrorReport
unwrap from main, so HEAD is the correct superset.

Build: :api, :core, :opensearch-sql-plugin, :legacy compileJava and
unit tests pass; spotlessCheck passes.

Signed-off-by: Kai Huang <ahkcs@amazon.com>

…ation

Brings the catch-up branch up to current upstream/main (4 commits since
this PR was opened) and current feature/mustang-ppl-integration (9
commits since this PR was opened), so the PR is mergeable into
feature/mustang-ppl-integration without conflicts.

Squashed (rather than two real merge commits) for the same DCO reason
the original commit was squashed: upstream commits authored by many
contributors with inconsistent or missing Signed-off-by trailers would
otherwise be brought into this PR's history.

Newer main commits absorbed (4):
- opensearch-project#5419 (LENGTH/REGEXP_REPLACE/DATE_TRUNC unified function spec)
- opensearch-project#5408 (datetime type normalization)
- opensearch-project#5414 (Gradle wrapper bump + @ignore exclusion)
- opensearch-project#5399 (FGAC-scoped SQL cursor continuation)

Newer feature commits absorbed (9):
- opensearch-project#5403 (analytics-engine optional dependency — major rewiring)
- opensearch-project#5407 (Carry CalciteEvalCommandIT through helper-managed index path)
- opensearch-project#5413 (Default plugins.calcite.enabled=true on unified path)
- opensearch-project#5415, opensearch-project#5416, opensearch-project#5417, opensearch-project#5409, opensearch-project#5400, opensearch-project#5406 (smaller carryovers + bumps)

Conflict resolutions (10 from main side, 3 from feature side):

api/spec/* (LanguageSpec, UnifiedFunctionSpec, UnifiedPplSpec,
UnifiedSqlSpec): took main. Main is a strict superset — adds
postAnalysisRules and preCompilationRules extension points, the new
FunctionSpecBuilder DSL, SCALAR category for length/regexp_replace/
date_trunc, the DatetimeExtension on PPL spec, and the CoreExtension
wiring on SQL spec. PR's RELEVANCE category is preserved unchanged.

api/UnifiedQueryPlanner.java, api/compiler/UnifiedQueryCompiler.java:
took main. Both adopt the new postAnalysisRules / preCompilationRules
hooks introduced in opensearch-project#5408 / opensearch-project#5419.

core/executor/QueryService.java: composed both sides — kept HEAD's
CalciteClassLoaderHelper.withCalciteClassLoader wrapper around main's
StageErrorHandler stage tracking. Same pattern as the original PR
resolution; both improvements are orthogonal.

legacy/plugin/RestSqlAction.java: took HEAD. The 3-way merge produced
a duplicated handleException/getRawErrorCode block; HEAD already
contained both the delegateToV2Engine refactor and the ErrorReport
unwrap from main, so HEAD is the correct superset.

integ-test/build.gradle: took feature. Both sides added the same
@ignore exclusion block; feature has alphabetical ordering and a more
detailed comment explaining the Gradle 9.4.1 TestEventReporterAsListener
cast bug.

integ-test/.../CalciteEvalCommandIT.java: composed both sides. Took
feature's helper-managed test_eval provisioning (createIndexByRestClient
+ isIndexExist guard, from opensearch-project#5407) so analytics-engine compatibility runs
get a parquet-backed index. Added back PR HEAD's test_eval_agent setup
(needed by the dotted-path eval tests for opensearch-project#5351) wrapped in its own
isIndexExist guard for the same parquet-aware idempotency.

plugin/.../TransportPPLQueryAction.java: took feature. PR opensearch-project#5403 made
analytics-engine an optional dependency by moving QueryPlanExecutor
from a required constructor parameter to an @Inject(optional=true)
setter. Feature's design supersedes our prior wiring.

plugin/.../SQLPlugin.java: took feature. The same opensearch-project#5403 simplification
removed loadExtensions/EngineExtensionsHolder/executionEngineExtensions
plumbing (no longer needed once analytics-engine is optionally bound).
Feature retains the createSqlAnalyticsRouter method this PR introduced.

plugin/.../config/EngineExtensionsHolder.java: deleted. Unreferenced
after taking feature's SQLPlugin/TransportPPLQueryAction; not present
on feature branch.

Build: :api, :core, :opensearch-sql-plugin, :legacy compileJava +
:integ-test compileTestJava all pass; unit tests pass; spotlessCheck
clean.

Signed-off-by: Kai Huang <ahkcs@amazon.com>

Single squashed commit on top of feature/mustang-ppl-integration that
absorbs upstream/main's commits not yet on the feature branch. Replaces
the prior catch-up squash (opensearch-project#5396 base + the original af831d3 rebase
commit) so this PR is a fast-forward into feature/mustang-ppl-integration.

Squashed (rather than a merge commit) because upstream main commits
were authored by many contributors with inconsistent or missing
Signed-off-by trailers; DCO would otherwise reject those commits.

Main commits absorbed (54 since divergence; 4 since the original
catch-up squash was made on 2026-04-30):
- opensearch-project#5419 (LENGTH/REGEXP_REPLACE/DATE_TRUNC unified function spec)
- opensearch-project#5408 (datetime type normalization)
- opensearch-project#5414 (Gradle wrapper bump + @ignore exclusion)
- opensearch-project#5399 (FGAC-scoped SQL cursor continuation)
- opensearch-project#5394 (SQL Vector Search), opensearch-project#5361 (OpenSearch 3.7), opensearch-project#5360 (unified SQL
  language spec), opensearch-project#5240 (PPL Union), and 46 others.

Conflict resolutions:

api/spec/* (LanguageSpec, UnifiedFunctionSpec, UnifiedPplSpec,
UnifiedSqlSpec): took main. Main is a strict superset — adds
postAnalysisRules and preCompilationRules extension points, the new
FunctionSpecBuilder DSL, SCALAR category for length/regexp_replace/
date_trunc, the DatetimeExtension on PPL spec, and the CoreExtension
wiring on SQL spec. RELEVANCE category is preserved unchanged.

api/UnifiedQueryPlanner.java, api/compiler/UnifiedQueryCompiler.java:
took main. Both adopt the new postAnalysisRules / preCompilationRules
hooks introduced in opensearch-project#5408 / opensearch-project#5419.

core/executor/QueryService.java: composed both sides — kept feature's
CalciteClassLoaderHelper.withCalciteClassLoader wrapper around main's
StageErrorHandler stage tracking; both improvements are orthogonal.

legacy/plugin/RestSqlAction.java: took feature. The 3-way merge
produced a duplicated handleException/getRawErrorCode block; feature
already contained both the delegateToV2Engine refactor and the
ErrorReport unwrap from main, so feature is the correct superset.

CLAUDE.md, docs/user/ppl/functions/condition.md: took main.

explain_streamstats_global{,_null_bucket}.yaml: took main (post-opensearch-project#5359
shape).

core/CalciteRelNodeVisitor + utils/PlanUtils: took main (collation
utility hoisted from CalciteRelNodeVisitor.backtrackForCollation into
PlanUtils.findInputCollation).

integ-test/CalciteNoPushdownIT.java: added CalciteMixedFieldTypeIT.

ppl/antlr/OpenSearchPPLParser.g4: added unionCommand.

ppl/calcite/CalcitePPLStreamstatsTest.java: added
testMultipleStreamstatsWithWindow.

integ-test/build.gradle: took feature. Both sides added the same
@ignore exclusion block; feature has alphabetical ordering and a more
detailed comment explaining the Gradle 9.4.1 cast bug.

integ-test/.../CalciteEvalCommandIT.java: composed both sides. Took
feature's helper-managed test_eval provisioning (createIndexByRestClient
+ isIndexExist guard, from opensearch-project#5407) so analytics-engine compatibility runs
get a parquet-backed index. Added the test_eval_agent setup (needed by
the dotted-path eval tests for opensearch-project#5351) wrapped in its own isIndexExist
guard for the same parquet-aware idempotency.

plugin/.../TransportPPLQueryAction.java, plugin/.../SQLPlugin.java:
took feature. PR opensearch-project#5403 made analytics-engine an optional dependency by
moving QueryPlanExecutor from a required constructor parameter to an
@Inject(optional=true) setter, and removed the loadExtensions /
EngineExtensionsHolder / executionEngineExtensions plumbing. Feature
retains the createSqlAnalyticsRouter method this catch-up introduced.

plugin/.../config/EngineExtensionsHolder.java: deleted (unreferenced
post-opensearch-project#5403; not present on feature).

Build: :api, :core, :opensearch-sql-plugin, :legacy compileJava +
:integ-test compileTestJava all pass; unit tests pass; spotlessCheck
clean.

Signed-off-by: Kai Huang <ahkcs@amazon.com>

…5397)

Single squashed commit on top of feature/mustang-ppl-integration that
absorbs upstream/main's commits not yet on the feature branch. Replaces
the prior catch-up squash (#5396 base + the original af831d3 rebase
commit) so this PR is a fast-forward into feature/mustang-ppl-integration.

Squashed (rather than a merge commit) because upstream main commits
were authored by many contributors with inconsistent or missing
Signed-off-by trailers; DCO would otherwise reject those commits.

Main commits absorbed (54 since divergence; 4 since the original
catch-up squash was made on 2026-04-30):
- #5419 (LENGTH/REGEXP_REPLACE/DATE_TRUNC unified function spec)
- #5408 (datetime type normalization)
- #5414 (Gradle wrapper bump + @ignore exclusion)
- #5399 (FGAC-scoped SQL cursor continuation)
- #5394 (SQL Vector Search), #5361 (OpenSearch 3.7), #5360 (unified SQL
  language spec), #5240 (PPL Union), and 46 others.

Conflict resolutions:

api/spec/* (LanguageSpec, UnifiedFunctionSpec, UnifiedPplSpec,
UnifiedSqlSpec): took main. Main is a strict superset — adds
postAnalysisRules and preCompilationRules extension points, the new
FunctionSpecBuilder DSL, SCALAR category for length/regexp_replace/
date_trunc, the DatetimeExtension on PPL spec, and the CoreExtension
wiring on SQL spec. RELEVANCE category is preserved unchanged.

api/UnifiedQueryPlanner.java, api/compiler/UnifiedQueryCompiler.java:
took main. Both adopt the new postAnalysisRules / preCompilationRules
hooks introduced in #5408 / #5419.

core/executor/QueryService.java: composed both sides — kept feature's
CalciteClassLoaderHelper.withCalciteClassLoader wrapper around main's
StageErrorHandler stage tracking; both improvements are orthogonal.

legacy/plugin/RestSqlAction.java: took feature. The 3-way merge
produced a duplicated handleException/getRawErrorCode block; feature
already contained both the delegateToV2Engine refactor and the
ErrorReport unwrap from main, so feature is the correct superset.

CLAUDE.md, docs/user/ppl/functions/condition.md: took main.

explain_streamstats_global{,_null_bucket}.yaml: took main (post-#5359
shape).

core/CalciteRelNodeVisitor + utils/PlanUtils: took main (collation
utility hoisted from CalciteRelNodeVisitor.backtrackForCollation into
PlanUtils.findInputCollation).

integ-test/CalciteNoPushdownIT.java: added CalciteMixedFieldTypeIT.

ppl/antlr/OpenSearchPPLParser.g4: added unionCommand.

ppl/calcite/CalcitePPLStreamstatsTest.java: added
testMultipleStreamstatsWithWindow.

integ-test/build.gradle: took feature. Both sides added the same
@ignore exclusion block; feature has alphabetical ordering and a more
detailed comment explaining the Gradle 9.4.1 cast bug.

integ-test/.../CalciteEvalCommandIT.java: composed both sides. Took
feature's helper-managed test_eval provisioning (createIndexByRestClient
+ isIndexExist guard, from #5407) so analytics-engine compatibility runs
get a parquet-backed index. Added the test_eval_agent setup (needed by
the dotted-path eval tests for #5351) wrapped in its own isIndexExist
guard for the same parquet-aware idempotency.

plugin/.../TransportPPLQueryAction.java, plugin/.../SQLPlugin.java:
took feature. PR #5403 made analytics-engine an optional dependency by
moving QueryPlanExecutor from a required constructor parameter to an
@Inject(optional=true) setter, and removed the loadExtensions /
EngineExtensionsHolder / executionEngineExtensions plumbing. Feature
retains the createSqlAnalyticsRouter method this catch-up introduced.

plugin/.../config/EngineExtensionsHolder.java: deleted (unreferenced
post-#5403; not present on feature).

Build: :api, :core, :opensearch-sql-plugin, :legacy compileJava +
:integ-test compileTestJava all pass; unit tests pass; spotlessCheck
clean.

Signed-off-by: Kai Huang <ahkcs@amazon.com>

Brings the branch up to current upstream/main (54 commits since the last
catch-up at opensearch-project#5397, divergence point 513e1b2). Preserves both parents
so commit lineage from main is retained on the feature branch.

### Main commits absorbed (54 since divergence)

Highlights:
- opensearch-project#5419 Register LENGTH/REGEXP_REPLACE/DATE_TRUNC in unified function spec
- opensearch-project#5408 Normalize datetime types for unified query API
- opensearch-project#5414 Gradle wrapper 9.4.1 bump + exclude @ignore classes
- opensearch-project#5399 [BugFix] Scope SQL cursor continuation to original query indices under FGAC
- opensearch-project#5394 [Feature] Support SQL Vector Search
- opensearch-project#5361 Version bump to OpenSearch 3.7 (Jackson 2 → 3 parser API)
- opensearch-project#5360 Define unified SQL language spec with composable extensions
- opensearch-project#5240 [FEATURE] Union command in PPL
- opensearch-project#5266 Initial implementation of report-builder interface
- opensearch-project#5278 isnotnull condition support
- opensearch-project#3922, opensearch-project#4659, opensearch-project#4800, opensearch-project#5099, opensearch-project#5169, opensearch-project#5172, opensearch-project#5175, opensearch-project#5185, opensearch-project#5347, opensearch-project#5370
  and other bugfixes
- 34 others (bugfixes, doc updates, infra)

### Conflict resolutions

Seven content conflicts resolved during the merge. Resolution kept the
feature branch's analytics-engine-path semantics where main's changes
would have regressed them.

- api/.../UnifiedQueryContext.java
  Blank-line-only conflict in Builder.build(); took main's tighter
  formatting (no extra blank).

- core/.../executor/QueryService.java
  Main reformatted executeWithCalcite without the
  CalciteClassLoaderHelper.withCalciteClassLoader() wrapper. Kept the
  feature-branch wrapping — required for analytics-engine classloader
  isolation — and the matching import. Same shape applies to
  explainWithCalcite which git auto-merged correctly.

- integ-test/build.gradle
  Both sides added @Ignore-class exclusions to work around the Gradle
  9.4.1 TestEventReporterAsListener ClassCastException. Took the
  feature-branch's detailed root-cause comment, kept ASCII ordering of
  the JSONRequestIT/JoinIT and SQLFunctionsIT/ShowIT/SourceFieldIT
  entries.

- integ-test/.../CalciteEvalCommandIT.java
  Feature branch wraps test-data PUTs in
  if (!TestUtils.isIndexExist(...)) for idempotency on the
  helper-managed-index analytics-engine compatibility run; main has the
  unguarded PUTs. Kept feature's idempotency guards for both test_eval
  and test_eval_agent.

- legacy/.../RestSqlAction.java
  Feature branch added delegateToV2Engine(...) (extracted from the
  analytics-engine routing path) and ALSO has handleException /
  getRestStatus / getRawErrorCode; main added the latter three in the
  same position. Kept feature's delegateToV2Engine, kept one copy of
  the helpers, removed the duplicate set that git produced.

- plugin/.../SQLPlugin.java
  Both sides expanded the executor import block. Kept the union:
  ExecutionEngine + ExecutionEngine.ExplainResponse + QueryType (all
  three are referenced in this file).

- plugin/.../transport/TransportPPLQueryAction.java
  Main now passes engine extensions to OpenSearchPluginModule via
  extensionsHolder.engines(). Feature creates a local pluginSettings
  for the unified-query handler. Combined both — kept the
  extensions-aware module construction *and* the pluginSettings /
  pluginSettingsRef wiring.

EngineExtensionsHolder is a new file from main (opensearch-project#5298) preserved as-is.

### Verification

- ./gradlew :api:compileJava :core:compileJava :legacy:compileJava
  :opensearch-sql-plugin:compileJava :integ-test:compileTestJava
  passes locally

Signed-off-by: Kai Huang <ahkcs@amazon.com>

Single squashed delivery of the long-running
feature/mustang-ppl-integration branch into main, consolidating 22
feature-branch PRs plus the conflict-resolved merge of current main.
Squashed because the feature branch's history includes commits with
missing or mismatched Signed-off-by trailers that block DCO at this
scope — the equivalent issue documented for the catch-up squashes
(opensearch-project#5397).

The feature branch f006e29 is retained for individual-commit lineage.

### What this delivers

Analytics-engine PPL integration — a new execution path that routes
Parquet-backed (non-Lucene) indices through an analytics engine while
keeping Lucene-backed indices on the existing v2 / Calcite paths.

Headline pieces:
- Query routing (opensearch-project#5267) — PPL queries against Parquet-backed indices
  hand off to the analytics-engine execution path; Lucene-backed indices
  continue through the legacy path
- Explain support (opensearch-project#5275) — EXPLAIN covers the analytics-engine path
- Profiling + UnifiedQueryParser (opensearch-project#5285) — migrates PPL parsing to the
  unified parser and wires profiling metrics through the analytics path
- extendedPlugins wiring (opensearch-project#5302) — analytics-engine attaches as an
  OpenSearch extension via SPI
- SQL REST endpoint integration (opensearch-project#5317) — same analytics-route fork
  applied to the SQL transport, plus delegateToV2Engine extraction in
  RestSqlAction
- Async QueryPlanExecutor (opensearch-project#5396) — async execution for analytics-engine
  plans + version bump to OpenSearch 3.7
- Optional dependency (opensearch-project#5403) — analytics-engine becomes an optional
  runtime dep so the SQL bundle is shippable without it
- Index-setting-based routing (opensearch-project#5429) — replaces the earlier
  table-name-prefix heuristic with an authoritative index-setting check

Supporting infrastructure:
- Gradle wrapper bump to 9.4.1 (opensearch-project#5406)
- Jar-hell exclusions for arrow-flight-rpc / httpcore5-h2 /
  httpcore5-reactive / httpclient5 (opensearch-project#5400, opensearch-project#5409)
- IT plumbing: CalciteEvalCommandIT / CalciteFieldFormatCommandIT
  carried through the helper-managed index path (opensearch-project#5407, opensearch-project#5417);
  CalciteReplaceCommandIT column-order-agnostic (opensearch-project#5415); @ignore'd
  Calcite ITs dropped from CalciteNoPushdownIT (opensearch-project#5416)
- plugins.calcite.enabled=true defaulted on the unified query path
  (opensearch-project#5413)
- PPL_REX_MAX_MATCH_LIMIT bridged into UnifiedQueryContext (opensearch-project#5418)
- Calcite tolerance fixes: array() default type (opensearch-project#5421),
  containsNestedAggregator flat-leaf schemas (opensearch-project#5423)
- Sandbox deps switched to analytics-api JDK 21 surface (opensearch-project#5426)

### Feature-branch commits squashed (22)

opensearch-project#5429, opensearch-project#5426, opensearch-project#5423, opensearch-project#5421, opensearch-project#5418, opensearch-project#5403, opensearch-project#5417, opensearch-project#5415, opensearch-project#5416, opensearch-project#5413,
opensearch-project#5407, opensearch-project#5409, opensearch-project#5406, opensearch-project#5400, opensearch-project#5396, opensearch-project#5317, opensearch-project#5302, opensearch-project#5285, opensearch-project#5275, opensearch-project#5267,
opensearch-project#5397, opensearch-project#5286

### Main commits absorbed via the merge (54)

Brings the branch up to current upstream/main (54 commits since the
last catch-up at opensearch-project#5397, divergence point 513e1b2). Highlights: opensearch-project#5419,
opensearch-project#5408, opensearch-project#5414, opensearch-project#5399, opensearch-project#5394, opensearch-project#5361, opensearch-project#5360, opensearch-project#5240, opensearch-project#5266, opensearch-project#5278, plus 44
others (bugfixes, doc updates, infra).

### Conflict resolutions (7)

Resolved during the merge of main into the feature branch. Resolution
kept the feature branch's analytics-engine-path semantics where main's
changes would have regressed them.

- api/.../UnifiedQueryContext.java
  Blank-line-only conflict; took main's tighter formatting.

- core/.../executor/QueryService.java
  Kept feature's CalciteClassLoaderHelper.withCalciteClassLoader(...)
  wrapping (required for analytics-engine classloader isolation) and
  the matching import.

- integ-test/build.gradle
  Kept feature's detailed root-cause comment on the Gradle 9.4.1
  TestEventReporterAsListener workaround; kept ASCII ordering of
  JSONRequestIT / JoinIT and SQLFunctionsIT / ShowIT / SourceFieldIT
  entries.

- integ-test/.../CalciteEvalCommandIT.java
  Kept feature's if (!TestUtils.isIndexExist(...)) idempotency guards
  on test_eval and test_eval_agent setup (needed for the helper-managed
  index analytics-engine compatibility run).

- legacy/.../RestSqlAction.java
  Kept feature's delegateToV2Engine(...) (extracted from the
  analytics-engine routing path). Both sides added handleException /
  getRestStatus / getRawErrorCode; removed the duplicate set git
  produced.

- plugin/.../SQLPlugin.java
  Took the union of imports: ExecutionEngine +
  ExecutionEngine.ExplainResponse + QueryType.

- plugin/.../transport/TransportPPLQueryAction.java
  Combined main's OpenSearchPluginModule(extensionsHolder.engines()) and
  feature's local pluginSettings / pluginSettingsRef wiring.

EngineExtensionsHolder.java is a new file from main (opensearch-project#5298) preserved
as-is.

### Compatibility / opt-in

The analytics-engine path is gated by the extendedPlugins extension
being installed (opensearch-project#5403 makes the dep optional). Clusters without
analytics-engine installed see no behavior change. Clusters with
analytics-engine installed route only Parquet-backed indices through
the new path (opensearch-project#5429 — by index setting).

### Verification

- ./gradlew :api:compileJava :core:compileJava :legacy:compileJava
  :opensearch-sql-plugin:compileJava :integ-test:compileTestJava passes
  locally

Signed-off-by: Kai Huang <ahkcs@amazon.com>

Single squashed delivery of the long-running
feature/mustang-ppl-integration branch into main, consolidating 22
feature-branch PRs plus the conflict-resolved merge of current main.
Squashed because the feature branch's history includes commits with
missing or mismatched Signed-off-by trailers that block DCO at this
scope — the equivalent issue documented for the catch-up squashes
(opensearch-project#5397).

The feature branch f006e29 is retained for individual-commit lineage.

### What this delivers

Analytics-engine PPL integration — a new execution path that routes
Parquet-backed (non-Lucene) indices through an analytics engine while
keeping Lucene-backed indices on the existing v2 / Calcite paths.

Headline pieces:
- Query routing (opensearch-project#5267) — PPL queries against Parquet-backed indices
  hand off to the analytics-engine execution path; Lucene-backed indices
  continue through the legacy path
- Explain support (opensearch-project#5275) — EXPLAIN covers the analytics-engine path
- Profiling + UnifiedQueryParser (opensearch-project#5285) — migrates PPL parsing to the
  unified parser and wires profiling metrics through the analytics path
- extendedPlugins wiring (opensearch-project#5302) — analytics-engine attaches as an
  OpenSearch extension via SPI
- SQL REST endpoint integration (opensearch-project#5317) — same analytics-route fork
  applied to the SQL transport, plus delegateToV2Engine extraction in
  RestSqlAction
- Async QueryPlanExecutor (opensearch-project#5396) — async execution for analytics-engine
  plans + version bump to OpenSearch 3.7
- Optional dependency (opensearch-project#5403) — analytics-engine becomes an optional
  runtime dep so the SQL bundle is shippable without it
- Index-setting-based routing (opensearch-project#5429, opensearch-project#5432) — replaces the earlier
  table-name-prefix heuristic with an authoritative index-setting check

Supporting infrastructure:
- Gradle wrapper bump to 9.4.1 (opensearch-project#5406)
- Jar-hell exclusions for arrow-flight-rpc / httpcore5-h2 /
  httpcore5-reactive / httpclient5 (opensearch-project#5400, opensearch-project#5409)
- IT plumbing: CalciteEvalCommandIT / CalciteFieldFormatCommandIT
  carried through the helper-managed index path (opensearch-project#5407, opensearch-project#5417);
  CalciteReplaceCommandIT column-order-agnostic (opensearch-project#5415); @ignore'd
  Calcite ITs dropped from CalciteNoPushdownIT (opensearch-project#5416)
- plugins.calcite.enabled=true defaulted on the unified query path
  (opensearch-project#5413)
- PPL_REX_MAX_MATCH_LIMIT bridged into UnifiedQueryContext (opensearch-project#5418)
- Calcite tolerance fixes: array() default type (opensearch-project#5421),
  containsNestedAggregator flat-leaf schemas (opensearch-project#5423)
- Sandbox deps switched to analytics-api JDK 21 surface (opensearch-project#5426)

### Feature-branch commits squashed (22)

opensearch-project#5432, opensearch-project#5429, opensearch-project#5426, opensearch-project#5423, opensearch-project#5421, opensearch-project#5418, opensearch-project#5403, opensearch-project#5417, opensearch-project#5415, opensearch-project#5416, opensearch-project#5413,
opensearch-project#5407, opensearch-project#5409, opensearch-project#5406, opensearch-project#5400, opensearch-project#5396, opensearch-project#5317, opensearch-project#5302, opensearch-project#5285, opensearch-project#5275, opensearch-project#5267,
opensearch-project#5397, opensearch-project#5286

### Main commits absorbed via the merge (54)

Brings the branch up to current upstream/main (54 commits since the
last catch-up at opensearch-project#5397, divergence point 513e1b2). Highlights: opensearch-project#5419,
opensearch-project#5408, opensearch-project#5414, opensearch-project#5399, opensearch-project#5394, opensearch-project#5361, opensearch-project#5360, opensearch-project#5240, opensearch-project#5266, opensearch-project#5278, plus 44
others (bugfixes, doc updates, infra).

### Conflict resolutions (7)

Resolved during the merge of main into the feature branch. Resolution
kept the feature branch's analytics-engine-path semantics where main's
changes would have regressed them.

- api/.../UnifiedQueryContext.java
  Blank-line-only conflict; took main's tighter formatting.

- core/.../executor/QueryService.java
  Kept feature's CalciteClassLoaderHelper.withCalciteClassLoader(...)
  wrapping (required for analytics-engine classloader isolation) and
  the matching import.

- integ-test/build.gradle
  Kept feature's detailed root-cause comment on the Gradle 9.4.1
  TestEventReporterAsListener workaround; kept ASCII ordering of
  JSONRequestIT / JoinIT and SQLFunctionsIT / ShowIT / SourceFieldIT
  entries.

- integ-test/.../CalciteEvalCommandIT.java
  Kept feature's if (!TestUtils.isIndexExist(...)) idempotency guards
  on test_eval and test_eval_agent setup (needed for the helper-managed
  index analytics-engine compatibility run).

- legacy/.../RestSqlAction.java
  Kept feature's delegateToV2Engine(...) (extracted from the
  analytics-engine routing path). Both sides added handleException /
  getRestStatus / getRawErrorCode; removed the duplicate set git
  produced.

- plugin/.../SQLPlugin.java
  Took the union of imports: ExecutionEngine +
  ExecutionEngine.ExplainResponse + QueryType.

- plugin/.../transport/TransportPPLQueryAction.java
  Combined main's OpenSearchPluginModule(extensionsHolder.engines()) and
  feature's local pluginSettings / pluginSettingsRef wiring.

EngineExtensionsHolder.java is a new file from main (opensearch-project#5298) preserved
as-is.

### Compatibility / opt-in

The analytics-engine path is gated by the extendedPlugins extension
being installed (opensearch-project#5403 makes the dep optional). Clusters without
analytics-engine installed see no behavior change. Clusters with
analytics-engine installed route only Parquet-backed indices through
the new path (opensearch-project#5429 — by index setting).

### Verification

- ./gradlew :api:compileJava :core:compileJava :legacy:compileJava
  :opensearch-sql-plugin:compileJava :integ-test:compileTestJava passes
  locally

Signed-off-by: Kai Huang <ahkcs@amazon.com>
Co-authored-by: bowenlan-amzn <bowenlan23@gmail.com>