HHH-19532 Add unwrap() method to StatelessSession/SharedSessionContract

Author: yrodiere

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

@@ -1499,4 +1499,9 @@ public interface Session extends SharedSessionContract, EntityManager {
 	 */
 	@Override @Deprecated(since = "6.0") @SuppressWarnings("rawtypes")
 	Query createQuery(CriteriaUpdate updateQuery);
+
+	@Override
+	default <T> T unwrap(Class<T> type) {
+		return SharedSessionContract.super.unwrap(type);
+	}
 }

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

@@ -10,6 +10,7 @@
 import java.util.function.Function;
 
 import jakarta.persistence.EntityGraph;
+import jakarta.persistence.PersistenceException;
 import org.hibernate.graph.RootGraph;
 import org.hibernate.jdbc.ReturningWork;
 import org.hibernate.jdbc.Work;
@@ -472,4 +473,28 @@ default <R> R fromTransaction(Function<? super Transaction,R> action) {
 		final Transaction transaction = beginTransaction();
 		return manageTransaction( transaction, transaction, action );
 	}
+
+	/**
+	 * Return an object of the specified type to allow access to
+	 * a provider-specific API.
+	 *
+	 * @param type the class of the object to be returned.
+	 * This is usually either the underlying class
+	 * implementing {@code SharedSessionContract} or an
+	 * interface it implements.
+	 * @return an instance of the specified class
+	 * @throws PersistenceException if the provider does not
+	 * support the given type
+	 */
+	default <T> T unwrap(Class<T> type) {
+		// Not checking type.isInstance(...) because some implementations
+		// might want to hide that they implement some types.
+		// Implementations wanting a more liberal behavior need to override this method.
+		if ( type.isAssignableFrom( SharedSessionContract.class ) ) {
+			return type.cast( this );
+		}
+
+		throw new PersistenceException(
+				"Hibernate cannot unwrap '" + getClass().getName() + "' as '" + type.getName() + "'" );
+	}
 }

hibernate-core/src/main/java/org/hibernate/internal/SessionImpl.java

@@ -2963,7 +2963,8 @@ public <T> T unwrap(Class<T> type) {
 			return type.cast( persistenceContext );
 		}
 
-		throw new PersistenceException( "Hibernate cannot unwrap EntityManager as '" + type.getName() + "'" );
+		throw new PersistenceException(
+				"Hibernate cannot unwrap '" + getClass().getName() + "' as '" + type.getName() + "'" );
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/internal/StatelessSessionImpl.java

@@ -9,6 +9,7 @@
 import java.util.Set;
 import java.util.function.BiConsumer;
 
+import jakarta.persistence.PersistenceException;
 import org.hibernate.AssertionFailure;
 import org.hibernate.FlushMode;
 import org.hibernate.HibernateException;
@@ -1433,6 +1434,18 @@ public Object loadFromSecondLevelCache(EntityPersister persister, EntityKey enti
 		return CacheLoadHelper.loadFromSecondLevelCache( this, instanceToLoad, lockMode, persister, entityKey );
 	}
 
+	@Override
+	public <T> T unwrap(Class<T> type) {
+		checkOpen();
+
+		if ( type.isInstance( this ) ) {
+			return type.cast( this );
+		}
+
+		throw new PersistenceException(
+				"Hibernate cannot unwrap '" + getClass().getName() + "' as '" + type.getName() + "'" );
+	}
+
 	private static final class MultiLoadOptions implements MultiIdLoadOptions {
 		private final  LockOptions lockOptions;