Register transaction coordinator as observer when session is waiting for auto close but coordinator is not shared

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

@@ -240,6 +240,15 @@ public abstract class AbstractSharedSessionContract implements SharedSessionCont
 		transactionCoordinator.invalidate();
 	}
 
+	protected void prepareForAutoClose() {
+		waitingForAutoClose = true;
+		closed = true;
+		// For non-shared transaction coordinators, we have to add the observer
+		if ( !isTransactionCoordinatorShared ) {
+			addSharedSessionTransactionObserver( transactionCoordinator );
+		}
+	}
+
 	@Override
 	public boolean shouldAutoJoinTransaction() {
 		return autoJoinTransactions;

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

@@ -377,8 +377,7 @@ public class SessionImpl
 			}
 			else {
 				//Otherwise, session auto-close will be enabled by shouldAutoCloseSession().
-				waitingForAutoClose = true;
-				closed = true;
+				prepareForAutoClose();
 			}
 		}
 		else {