Fix closing cases

Author: fredericDelaporte

src/AsyncGenerator.yml

@@ -60,8 +60,12 @@
       name: BestGuessEntityName
       containingTypeName: ISessionImplementor
     - conversion: Ignore
-      name: Contains
+      name: CloseSessionFromSystemTransaction
       containingTypeName: ISessionImplementor
+# TODO 6.0: Remove ignore rule for IStatelessSession.Close
+    - conversion: Ignore
+      name: Close
+      containingTypeName: IStatelessSession
     - conversion: Ignore
       name: GetUnsavedVersionValue
       containingTypeName: UnsavedValueFactory

src/NHibernate/Async/Impl/StatelessSessionImpl.cs

@@ -322,6 +322,24 @@ public async Task ManagedFlushAsync(CancellationToken cancellationToken)
 
 		#region IStatelessSession Members
 
+		public async Task ManagedCloseAsync(CancellationToken cancellationToken)
+		{
+			cancellationToken.ThrowIfCancellationRequested();
+			using (BeginContext())
+			{
+				if (IsClosed)
+				{
+					throw new SessionException("Session was already closed!");
+				}
+				// We need to flush the batcher. Otherwise it may have pending operations which will never reach the database,
+				// although a stateless session is not supposed to retain anything in memory and so should not need any explicit
+				// flush from users.
+				await (FlushAsync(cancellationToken)).ConfigureAwait(false);
+				CloseConnectionManager();
+				SetClosed();
+			}
+		}
+
 		/// <summary> Insert a entity.</summary>
 		/// <param name="entity">A new transient instance </param>
 		/// <param name="cancellationToken">A cancellation token that can be used to cancel the work</param>

src/NHibernate/Impl/StatelessSessionImpl.cs

@@ -438,6 +438,10 @@ public void ManagedClose()
 				{
 					throw new SessionException("Session was already closed!");
 				}
+				// We need to flush the batcher. Otherwise it may have pending operations which will never reach the database,
+				// although a stateless session is not supposed to retain anything in memory and so should not need any explicit
+				// flush from users.
+				Flush();
 				CloseConnectionManager();
 				SetClosed();
 			}
@@ -786,6 +790,10 @@ public void Dispose()
 				// with a null ref rather than silently leaking a session. And then fix the synchronization.
 				if (TransactionContext != null && TransactionContext.CanFlushOnSystemTransactionCompleted)
 				{
+					// We need to flush the batcher. Otherwise it may have pending operations which will never reach the database,
+					// although a stateless session is not supposed to retain anything in memory and so should not need any explicit
+					// flush from users.
+					Flush();
 					TransactionContext.ShouldCloseSessionOnSystemTransactionCompleted = true;
 					return;
 				}