Pass timeout to TimeoutRejectedException

src/Polly/Timeout/AsyncTimeoutEngine.cs

@@ -46,7 +46,7 @@ internal static async Task<TResult> ImplementationAsync<TResult>(
             if (ex is OperationCanceledException && timeoutCancellationTokenSource.IsCancellationRequested)
             {
                 await onTimeoutAsync(context, timeout, actionTask, ex).ConfigureAwait(continueOnCapturedContext);
-                throw new TimeoutRejectedException("The delegate executed asynchronously through TimeoutPolicy did not complete within the timeout.", ex);
+                throw new TimeoutRejectedException("The delegate executed asynchronously through TimeoutPolicy did not complete within the timeout.", timeout, ex);
             }
 
             throw;

src/Polly/Timeout/TimeoutEngine.cs

@@ -62,7 +62,7 @@ internal static TResult Implementation<TResult>(
             if (ex is OperationCanceledException && timeoutCancellationTokenSource.IsCancellationRequested)
             {
                 onTimeout(context, timeout, actionTask, ex);
-                throw new TimeoutRejectedException("The delegate executed through TimeoutPolicy did not complete within the timeout.", ex);
+                throw new TimeoutRejectedException("The delegate executed through TimeoutPolicy did not complete within the timeout.", timeout, ex);
             }
 
             throw;

test/Polly.Specs/Timeout/TimeoutAsyncSpecs.cs

@@ -385,10 +385,12 @@ public async Task Should_throw_when_timeout_is_less_than_execution_duration__pes
 
         var policy = Policy.TimeoutAsync(timeout, TimeoutStrategy.Pessimistic);
 
-        await Should.ThrowAsync<TimeoutRejectedException>(() => policy.ExecuteAsync(async () =>
+        var exception = await Should.ThrowAsync<TimeoutRejectedException>(() => policy.ExecuteAsync(async () =>
         {
             await SystemClock.SleepAsync(TimeSpan.FromSeconds(3), CancellationToken);
         }));
+
+        exception.Timeout.ShouldBe(timeout);
     }
 
     [Fact]

test/Polly.Specs/Timeout/TimeoutSpecs.cs

@@ -340,9 +340,12 @@ public void Should_be_able_to_configure_without_an_exception()
     [Fact]
     public void Should_throw_when_timeout_is_less_than_execution_duration__pessimistic()
     {
-        var policy = Policy.Timeout(TimeSpan.FromMilliseconds(50), TimeoutStrategy.Pessimistic);
+        var timeout = TimeSpan.FromMilliseconds(50);
+        var policy = Policy.Timeout(timeout, TimeoutStrategy.Pessimistic);
 
-        Should.Throw<TimeoutRejectedException>(() => policy.Execute(() => SystemClock.Sleep(TimeSpan.FromSeconds(3), CancellationToken)));
+        var exception = Should.Throw<TimeoutRejectedException>(() => policy.Execute(() => SystemClock.Sleep(TimeSpan.FromSeconds(3), CancellationToken)));
+
+        exception.Timeout.ShouldBe(timeout);
     }
 
     [Fact]