Forward port release notes for v8.16.4

Author: elasticsearchmachine

docs/reference/migration/migrate_8_16.asciidoc

@@ -9,6 +9,9 @@ your application to {es} 8.16.
 
 See also <<release-highlights>> and <<es-release-notes>>.
 
+coming::[8.16.0]
+
+
 [discrete]
 [[breaking-changes-8.16]]
 === Breaking changes

docs/reference/release-notes.asciidoc

@@ -7,8 +7,10 @@
 This section summarizes the changes in each release.
 
 * <<release-notes-8.18.0>>
+* <<release-notes-8.17.2>>
 * <<release-notes-8.17.1>>
 * <<release-notes-8.17.0>>
+* <<release-notes-8.16.4>>
 * <<release-notes-8.16.3>>
 * <<release-notes-8.16.2>>
 * <<release-notes-8.16.1>>
@@ -83,8 +85,10 @@ This section summarizes the changes in each release.
 --
 
 include::release-notes/8.18.0.asciidoc[]
+include::release-notes/8.17.2.asciidoc[]
 include::release-notes/8.17.1.asciidoc[]
 include::release-notes/8.17.0.asciidoc[]
+include::release-notes/8.16.4.asciidoc[]
 include::release-notes/8.16.3.asciidoc[]
 include::release-notes/8.16.2.asciidoc[]
 include::release-notes/8.16.1.asciidoc[]

docs/reference/release-notes/8.16.4.asciidoc

@@ -0,0 +1,42 @@
+[[release-notes-8.16.4]]
+== {es} version 8.16.4
+
+Also see <<breaking-changes-8.16,Breaking changes in 8.16>>.
+
+[[bug-8.16.4]]
+[float]
+=== Bug fixes
+
+Aggregations::
+* Aggregations cancellation after collection {es-pull}120944[#120944] (issue: {es-issue}108701[#108701])
+
+Data streams::
+* Map `scope.name` as a dimension {es-pull}120590[#120590]
+
+ES|QL::
+* Use `field_caps` native nested fields filtering {es-pull}117201[#117201] (issue: {es-issue}117054[#117054])
+
+Mapping::
+* Fix synthetic source issue with deeply nested ignored source fields {es-pull}121715[#121715]
+
+Ranking::
+* Fix LTR rescorer throws 'local model reference is null' on multi-shards index when explained is enabled {es-pull}120717[#120717] (issue: {es-issue}120739[#120739])
+* LTR sometines throw `NullPointerException:` Cannot read field "approximation" because "top" is null {es-pull}120809[#120809]
+* Normalize negative scores for `text_similarity_reranker` retriever {es-pull}120930[#120930] (issue: {es-issue}120201[#120201])
+* Update Text Similarity Reranker to Properly Handle Aliases {es-pull}120062[#120062] (issue: {es-issue}119617[#119617])
+
+Search::
+* Fix potential file leak in ES816BinaryQuantizedVectorsWriter {es-pull}120014[#120014] (issue: {es-issue}119981[#119981])
+
+Snapshot/Restore::
+* Cheaper snapshot-related `toString()` impls {es-pull}121283[#121283]
+* Issue S3 web identity token refresh call with sufficient permissions {es-pull}119748[#119748] (issue: {es-issue}119747[#119747])
+
+[[enhancement-8.16.4]]
+[float]
+=== Enhancements
+
+Ingest Node::
+* Improve memory aspects of enrich cache {es-pull}120256[#120256] (issues: {es-issue}96050[#96050], {es-issue}120021[#120021])
+
+

docs/reference/release-notes/highlights.asciidoc

@@ -49,6 +49,20 @@ rank_vectors mapping for late-interaction second order ranking (#118804)
 
 {es-pull}119601[#119601]
 
+[discrete]
+[[enable_lookup_join_in_non_snapshot_builds]]
+=== Enable LOOKUP JOIN in non-snapshot builds
+This effectively releases LOOKUP JOIN into tech preview. Docs will
+follow in a separate PR.
+
+- Enable the lexing/grammar for LOOKUP JOIN in non-snapshot builds.
+- Remove the grammar for the unsupported `| JOIN ...` command (without `LOOKUP` as first keyword). The way the lexer modes work, otherwise we'd also have to enable `| JOIN ...` syntax on non-snapshot builds and would have to add additional validation to provide appropriate error messages.
+- Remove grammar for `LOOKUP JOIN index AS ...` because qualifiers are not yet supported. Otherwise we'd have to put in additional validation as well to prevent such queries.
+
+Also fix https://github.com/elastic/elasticsearch/issues/121185
+
+{es-pull}121193[#121193]
+
 // end::notable-highlights[]