expand a doc section about SS

Author: gavinking

documentation/src/main/asciidoc/introduction/Querying.adoc

@@ -400,7 +400,7 @@ List<Book> matchingBooks = selection.createQuery(session).getResultList();
 Notice that:
 
 - The link:{doc-javadoc-url}org/hibernate/query/restriction/Restriction.html[`Restriction`] interface has static methods for constructing a variety of different kinds of restriction in a completely typesafe way.
-- Similarly, the link:{doc-javadoc-url}org/hibernate/query/Order.html[`Order`] class has a variety of static methods for constructing different kinds of ordering criteria.
+- Similarly, the link:{doc-javadoc-url}org/hibernate/query/Order.html[`Order`] interface has a variety of static methods for constructing different kinds of sorting criteria.
 
 We need the following methods of link:{doc-javadoc-url}org/hibernate/query/programmatic/SelectionSpecification.html[`SelectionSpecification`]:
 

documentation/src/main/asciidoc/introduction/Tuning.adoc

@@ -934,12 +934,34 @@ NOTE: There's no `flush()` operation, and so `update()` is always explicit.
 
 In certain circumstances, this makes stateless sessions easier to work with and simpler to reason about, but with the caveat that a stateless session is much more vulnerable to data aliasing effects, since it's easy to get two non-identical Java objects which both represent the same row of a database table.
 
+Consider the following fragments:
+
+[source,java]
+----
+var b1 = statelessSession.get(Book.class, isbn);
+var b2 = statelessSession.get(Book.class, isbn);
+assert b1 == b2;  // fails
+----
+[source,java]
+----
+var b1 = statelessSession.get(Book.class, isbn);
+var b2 = statelessSession.get(Book.class, isbn);
+statelessSession.fetch(b1.publisher);
+statelessSession.fetch(b2.publisher);
+assert b1.publisher == b2.publisher;  // fails
+----
+
+In a stateful session, entity instances are canonicalized by primary key, and so we don't usually have two different objects representing a single row.
+No such canonicalization exists across invocations of a stateless session.
+In a stateless session, both the assertions fail.
+
 [%unbreakable]
 [CAUTION]
 ====
 If we use `fetch()` in a stateless session, we can very easily obtain two objects representing the same database row!
 ====
 
+But there are also some advantages to this model.
 In particular, the absence of a persistence context means that we can safely perform bulk-processing tasks without allocating huge quantities of memory.
 Use of a `StatelessSession` alleviates the need to call: