update news item

Author: hmottestad

site/content/news/rdf4j-530-M2.md

@@ -6,7 +6,14 @@ categories: ["news"]
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 Milestone number 2 of the upcoming 5.3.0 release of RDF4J is now available for download.
 
-RDF4J 5.3.0 is a minor release focusing on ... .
+RDF4J 5.3.0 is a minor release focusing on stability and getting the code ready for the next major release.
+
+### Notable changes in 5.3.0 M2
+
+ - SHACL validation can now be configured more precisely for inferred data ([GH-5676](https://github.com/eclipse-rdf4j/rdf4j/issues/5676)). If a shape (or global SHACL setting) disables inferred statements, underlying sails must emit inferred-aware callbacks by implementing `statementAdded(Statement, boolean inferred)` and `statementRemoved(Statement, boolean inferred)` in `SailConnectionListener`.
+ - The new query renderer introduced in M1 is improved with additional parser/renderer fixes, including `FILTER NOT EXISTS` rendering ([GH-5561](https://github.com/eclipse-rdf4j/rdf4j/issues/5561)). If you subclass `TupleExprBuilder` and override `createAnonVar()`, consider also overriding the newer specialized methods used by renderer-aware parsing: `createAnonCollectionVar()`, `createAnonBnodeVar()`, `createAnonHavingVar()`, and `createAnonPathVar(boolean)`.
+ - `Var` remains extensible through SPI (as introduced in M1): use `Var.of(...)` factories, provide a custom `Var.Provider` (`newVar(...)` and optionally `cloneVar(...)`), and register via `META-INF/services/org.eclipse.rdf4j.query.algebra.Var$Provider` or the `org.eclipse.rdf4j.query.algebra.Var.provider` system property.
+ - Additional end-user fixes include support for refining JSON-LD `@context` ([GH-5573](https://github.com/eclipse-rdf4j/rdf4j/issues/5573)) and major LuceneSail transaction performance improvements ([GH-5291](https://github.com/eclipse-rdf4j/rdf4j/issues/5291)).
 
 This milestone build is not yet feature-complete, but we are putting it out to receive early feedback on all the improvements we have put in.