more info about the metamodel in the javadoc for SessionFactory

hibernate-core/src/main/java/org/hibernate/SessionFactory.java

@@ -88,12 +88,30 @@ import static org.hibernate.internal.TransactionManagement.manageTransaction;
  * used in a sophisticated way by libraries or frameworks to implement generic
  * concerns involving entity classes.
  * <p>
+ * When the Metamodel Generator is used, elements of this metamodel may also
+ * be obtained in a typesafe way, via the generated metamodel classes. For
+ * an entity class {@code Book}, the generated {@code Book_} class has:
+ * <ul>
+ * <li>a single member named {@code class_} of type
+ *     {@link jakarta.persistence.metamodel.EntityType EntityType&lt;Book&gt;},
+ *     and
+ * <li>a member for each persistent attribute of {@code Book}, for example,
+ *     {@code title} of type {@link jakarta.persistence.metamodel.SingularAttribute
+ *     SingularAttribute&lt;Book,String&gt;}.
+ * </ul>
+ * <p>
+ * Use of these statically-typed metamodel references is the preferred way of
+ * working with the {@linkplain jakarta.persistence.criteria.CriteriaBuilder
+ * criteria query API}, and with {@linkplain EntityGraph}s.
+ * <p>
  * The factory also {@linkplain #getSchemaManager() provides} a
  * {@link SchemaManager} which allows, as a convenience for writing tests:
  * <ul>
  * <li>programmatic {@linkplain SchemaManager#exportMappedObjects(boolean)
  *     schema export} and {@linkplain SchemaManager#dropMappedObjects(boolean)
- *     schema removal}, and
+ *     schema removal},
+ * <li>schema {@linkplain SchemaManager#validateMappedObjects() validation},
+ *     and
  * <li>an operation for {@linkplain SchemaManager#truncateMappedObjects()
  *     cleaning up} data left behind by tests.
  * </ul>