Make the commit delay increment overridable (#330)

Co-authored-by: Daniel Marbach <danielmarbach@users.noreply.github.com>

src/NServiceBus.TransactionalSession.Tests/ApprovalFiles/APIApprovals.Approve.approved.txt

@@ -20,6 +20,7 @@ namespace NServiceBus.TransactionalSession
     public abstract class OpenSessionOptions
     {
         protected OpenSessionOptions() { }
+        public System.TimeSpan CommitDelayIncrement { get; set; }
         protected NServiceBus.Extensibility.ContextBag Extensions { get; }
         public System.TimeSpan MaximumCommitDuration { get; set; }
         public System.Collections.Generic.IDictionary<string, string> Metadata { get; }

src/NServiceBus.TransactionalSession/OpenSessionOptions.cs

@@ -31,9 +31,14 @@ public abstract class OpenSessionOptions
         /// The maximum duration the transaction is allowed to attempt to atomically commit.
         /// </summary>
         /// <remarks>The actual total transaction time observed might be longer, taking into account delays in the transport due to latency, delayed delivery and more.</remarks>
+        /// <remarks>Defaults to <code>TimeSpan.FromSeconds(15)</code></remarks>
         public TimeSpan MaximumCommitDuration { get; set; } = TimeSpan.FromSeconds(15);
 
-        internal TimeSpan CommitDelayIncrement { get; set; } = TimeSpan.FromSeconds(2);
+        /// <summary>
+        /// The time increment used to delay the commit of the transactional session when the outbox record is not yet in the storage.
+        /// </summary>
+        /// <remarks>Defaults to <code>TimeSpan.FromSeconds(2)</code></remarks>
+        public TimeSpan CommitDelayIncrement { get; set; } = TimeSpan.FromSeconds(2);
 
         Dictionary<string, string> metadata;
     }