diff --git a/src/modules/Elsa.Workflows.Core/Contexts/ActivityExecutionContext.cs b/src/modules/Elsa.Workflows.Core/Contexts/ActivityExecutionContext.cs
index f545b0881..5393a9f80 100644
--- a/src/modules/Elsa.Workflows.Core/Contexts/ActivityExecutionContext.cs
+++ b/src/modules/Elsa.Workflows.Core/Contexts/ActivityExecutionContext.cs
@@ -198,7 +198,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// <param name="completionCallback">An optional callback to invoke when the activity completes.</param>
     /// <param name="tag">An optional tag to associate with the activity execution.</param>
     /// <param name="variables">An optional list of variables to declare with the activity execution.</param>
-    public ValueTask ScheduleActivityAsync(IActivity? activity, ActivityCompletionCallback? completionCallback, object? tag = default, IEnumerable<Variable>? variables = default)
+    public ValueTask ScheduleActivityAsync(IActivity? activity, ActivityCompletionCallback? completionCallback, object? tag = null, IEnumerable<Variable>? variables = null)
     {
         var options = new ScheduleWorkOptions
         {
@@ -214,7 +214,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// </summary>
     /// <param name="activity">The activity to schedule.</param>
     /// <param name="options">The options used to schedule the activity.</param>
-    public async ValueTask ScheduleActivityAsync(IActivity? activity, ScheduleWorkOptions? options = default)
+    public async ValueTask ScheduleActivityAsync(IActivity? activity, ScheduleWorkOptions? options = null)
     {
         await ScheduleActivityAsync(activity, this, options);
     }
@@ -225,7 +225,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// <param name="activity">The activity to schedule.</param>
     /// <param name="owner">The activity execution context that owns the scheduled activity.</param>
     /// <param name="options">The options used to schedule the activity.</param>
-    public async ValueTask ScheduleActivityAsync(IActivity? activity, ActivityExecutionContext? owner, ScheduleWorkOptions? options = default)
+    public async ValueTask ScheduleActivityAsync(IActivity? activity, ActivityExecutionContext? owner, ScheduleWorkOptions? options = null)
     {
         var activityNode = activity != null
             ? WorkflowExecutionContext.FindNodeByActivity(activity) ?? throw new InvalidOperationException("The specified activity is not part of the workflow.")
@@ -239,7 +239,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// <param name="activityNode">The activity node to schedule.</param>
     /// <param name="owner">The activity execution context that owns the scheduled activity.</param>
     /// <param name="options">The options used to schedule the activity.</param>
-    public async ValueTask ScheduleActivityAsync(ActivityNode? activityNode, ActivityExecutionContext? owner = default, ScheduleWorkOptions? options = default)
+    public async ValueTask ScheduleActivityAsync(ActivityNode? activityNode, ActivityExecutionContext? owner = null, ScheduleWorkOptions? options = null)
     {
         if (this.GetIsBackgroundExecution())
         {
@@ -261,7 +261,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
                         Variables = options?.Variables?.ToList(),
                         Input = options?.Input
                     }
-                    : default
+                    : null
             };
 
             var scheduledActivities = this.GetBackgroundScheduledActivities().ToList();
@@ -303,7 +303,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// <param name="completionCallback">The callback to invoke when the activities complete.</param>
     /// <param name="tag">An optional tag to associate with the activity execution.</param>
     /// <param name="variables">An optional list of variables to declare with the activity execution.</param>
-    public ValueTask ScheduleActivities(IEnumerable<IActivity?> activities, ActivityCompletionCallback? completionCallback, object? tag = default, IEnumerable<Variable>? variables = default)
+    public ValueTask ScheduleActivities(IEnumerable<IActivity?> activities, ActivityCompletionCallback? completionCallback, object? tag = null, IEnumerable<Variable>? variables = null)
     {
         var options = new ScheduleWorkOptions
         {
@@ -319,7 +319,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// </summary>
     /// <param name="activities">The activities to schedule.</param>
     /// <param name="options">The options used to schedule the activities.</param>
-    public async ValueTask ScheduleActivities(IEnumerable<IActivity?> activities, ScheduleWorkOptions? options = default)
+    public async ValueTask ScheduleActivities(IEnumerable<IActivity?> activities, ScheduleWorkOptions? options = null)
     {
         foreach (var activity in activities)
             await ScheduleActivityAsync(activity, options);
@@ -331,7 +331,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// <param name="payloads">The payloads to create bookmarks for.</param>
     /// <param name="callback">An optional callback that is invoked when the bookmark is resumed.</param>
     /// <param name="includeActivityInstanceId">Whether or not the activity instance ID should be included in the bookmark payload.</param>
-    public void CreateBookmarks(IEnumerable<object> payloads, ExecuteActivityDelegate? callback = default, bool includeActivityInstanceId = true)
+    public void CreateBookmarks(IEnumerable<object> payloads, ExecuteActivityDelegate? callback = null, bool includeActivityInstanceId = true)
     {
         foreach (var payload in payloads)
             CreateBookmark(new CreateBookmarkArgs
@@ -360,7 +360,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// <param name="callback">An optional callback that is invoked when the bookmark is resumed.</param>
     /// <param name="metadata">Custom properties to associate with the bookmark.</param>
     /// <returns>The created bookmark.</returns>
-    public Bookmark CreateBookmark(ExecuteActivityDelegate callback, IDictionary<string, string>? metadata = default)
+    public Bookmark CreateBookmark(ExecuteActivityDelegate callback, IDictionary<string, string>? metadata = null)
     {
         return CreateBookmark(new CreateBookmarkArgs
         {
@@ -377,7 +377,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// <param name="includeActivityInstanceId">Whether or not the activity instance ID should be included in the bookmark payload.</param>
     /// <param name="customProperties">Custom properties to associate with the bookmark.</param>
     /// <returns>The created bookmark.</returns>
-    public Bookmark CreateBookmark(object stimulus, ExecuteActivityDelegate callback, bool includeActivityInstanceId = true, IDictionary<string, string>? customProperties = default)
+    public Bookmark CreateBookmark(object stimulus, ExecuteActivityDelegate callback, bool includeActivityInstanceId = true, IDictionary<string, string>? customProperties = null)
     {
         return CreateBookmark(new CreateBookmarkArgs
         {
@@ -395,7 +395,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// <param name="includeActivityInstanceId">Specifies whether to include the activity instance ID in the bookmark information. Defaults to true.</param>
     /// <param name="customProperties">Additional custom properties to associate with the bookmark. Defaults to null.</param>
     /// <returns>The created bookmark.</returns>
-    public Bookmark CreateBookmark(object stimulus, bool includeActivityInstanceId, IDictionary<string, string>? customProperties = default)
+    public Bookmark CreateBookmark(object stimulus, bool includeActivityInstanceId, IDictionary<string, string>? customProperties = null)
     {
         return CreateBookmark(new CreateBookmarkArgs
         {
@@ -411,9 +411,9 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// <param name="stimulus">The payload to associate with the bookmark.</param>
     /// <param name="metadata">Custom properties to associate with the bookmark.</param>
     /// <returns>The created bookmark.</returns>
-    public Bookmark CreateBookmark(object stimulus, IDictionary<string, string>? metadata = default)
+    public Bookmark CreateBookmark(object stimulus, IDictionary<string, string>? metadata = null)
     {
-        return CreateBookmark(new CreateBookmarkArgs
+        return CreateBookmark(new()
         {
             Stimulus = stimulus,
             Metadata = metadata
@@ -424,7 +424,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// Creates a bookmark so that this activity can be resumed at a later time.
     /// Creating a bookmark will automatically suspend the workflow after all pending activities have executed.
     /// </summary>
-    public Bookmark CreateBookmark(CreateBookmarkArgs? options = default)
+    public Bookmark CreateBookmark(CreateBookmarkArgs? options = null)
     {
         var payload = options?.Stimulus;
         var callback = options?.Callback;
@@ -569,7 +569,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// </summary>
     /// <param name="output">The output.</param>
     /// <returns>The output value.</returns>
-    public object? Get(Output? output) => output == null ? default : Get(output.MemoryBlockReference());
+    public object? Get(Output? output) => output == null ? null : Get(output.MemoryBlockReference());
 
     /// <summary>
     /// Gets the value of the specified memory block.
@@ -593,7 +593,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     public T? Get<T>(MemoryBlockReference blockReference)
     {
         var value = Get(blockReference);
-        return value != default ? value.ConvertTo<T>() : default;
+        return value != null ? value.ConvertTo<T>() : default;
     }
 
     /// <summary>
@@ -628,7 +628,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// <param name="blockReference">The memory block reference.</param>
     /// <param name="value">The value to set.</param>
     /// <param name="configure">An optional callback that can be used to configure the memory block.</param>
-    public void Set(MemoryBlockReference blockReference, object? value, Action<MemoryBlock>? configure = default) => ExpressionExecutionContext.Set(blockReference, value, configure);
+    public void Set(MemoryBlockReference blockReference, object? value, Action<MemoryBlock>? configure = null) => ExpressionExecutionContext.Set(blockReference, value, configure);
 
     /// <summary>
     /// Sets a value at the specified output.
@@ -637,7 +637,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// <param name="value">The value to set.</param>
     /// <param name="outputName">The name of the output.</param>
     /// <typeparam name="T">The type of the output.</typeparam>
-    public void Set<T>(Output<T>? output, T? value, [CallerArgumentExpression("output")] string? outputName = default) => Set((Output?)output, value, outputName);
+    public void Set<T>(Output<T>? output, T? value, [CallerArgumentExpression("output")] string? outputName = null) => Set((Output?)output, value, outputName);
 
     /// <summary>
     /// Sets a value at the specified output.
@@ -645,7 +645,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
     /// <param name="output">The output.</param>
     /// <param name="value">The value to set.</param>
     /// <param name="outputName">The name of the output.</param>
-    public void Set(Output? output, object? value, [CallerArgumentExpression("output")] string? outputName = default)
+    public void Set(Output? output, object? value, [CallerArgumentExpression("output")] string? outputName = null)
     {
         // Store the value in the expression execution memory block.
         ExpressionExecutionContext.Set(output, value);
@@ -667,7 +667,7 @@ public partial class ActivityExecutionContext : IExecutionContext, IDisposable
 
     private MemoryBlock? GetMemoryBlock(MemoryBlockReference locationBlockReference)
     {
-        return ExpressionExecutionContext.TryGetBlock(locationBlockReference, out var memoryBlock) ? memoryBlock : default;
+        return ExpressionExecutionContext.TryGetBlock(locationBlockReference, out var memoryBlock) ? memoryBlock : null;
     }
 
     void IDisposable.Dispose()
diff --git a/src/modules/Elsa.Workflows.Core/Extensions/ActivityExecutionContextExtensions.cs b/src/modules/Elsa.Workflows.Core/Extensions/ActivityExecutionContextExtensions.cs
index a0fc4e7ad..090cff8b8 100644
--- a/src/modules/Elsa.Workflows.Core/Extensions/ActivityExecutionContextExtensions.cs
+++ b/src/modules/Elsa.Workflows.Core/Extensions/ActivityExecutionContextExtensions.cs
@@ -25,13 +25,13 @@ public static partial class ActivityExecutionContextExtensions
     /// <summary>
     /// Attempts to get a value from the input provided via <see cref="WorkflowExecutionContext"/>. If a value was found, an attempt is made to convert it into the specified type <code>T</code>.
     /// </summary>
-    public static bool TryGetWorkflowInput<T>(this ActivityExecutionContext context, string key, out T value, JsonSerializerOptions? serializerOptions = default)
+    public static bool TryGetWorkflowInput<T>(this ActivityExecutionContext context, string key, out T value, JsonSerializerOptions? serializerOptions = null)
     {
         var wellKnownTypeRegistry = context.GetRequiredService<IWellKnownTypeRegistry>();
 
         if (context.WorkflowInput.TryGetValue(key, out var v))
         {
-            value = v.ConvertTo<T>(new ObjectConverterOptions(serializerOptions, wellKnownTypeRegistry))!;
+            value = v.ConvertTo<T>(new(serializerOptions, wellKnownTypeRegistry))!;
             return true;
         }
 
@@ -42,15 +42,15 @@ public static partial class ActivityExecutionContextExtensions
     /// <summary>
     /// Gets a value from the input provided via <see cref="WorkflowExecutionContext"/>. If a value was found, an attempt is made to convert it into the specified type <code>T</code>.
     /// </summary>
-    public static T GetWorkflowInput<T>(this ActivityExecutionContext context, JsonSerializerOptions? serializerOptions = default) => context.GetWorkflowInput<T>(typeof(T).Name, serializerOptions);
+    public static T GetWorkflowInput<T>(this ActivityExecutionContext context, JsonSerializerOptions? serializerOptions = null) => context.GetWorkflowInput<T>(typeof(T).Name, serializerOptions);
 
     /// <summary>
     /// Gets a value from the input provided via <see cref="WorkflowExecutionContext"/>. If a value was found, an attempt is made to convert it into the specified type <code>T</code>.
     /// </summary>
-    public static T GetWorkflowInput<T>(this ActivityExecutionContext context, string key, JsonSerializerOptions? serializerOptions = default)
+    public static T GetWorkflowInput<T>(this ActivityExecutionContext context, string key, JsonSerializerOptions? serializerOptions = null)
     {
         var wellKnownTypeRegistry = context.GetRequiredService<IWellKnownTypeRegistry>();
-        return context.WorkflowInput[key].ConvertTo<T>(new ObjectConverterOptions(serializerOptions, wellKnownTypeRegistry))!;
+        return context.WorkflowInput[key].ConvertTo<T>(new(serializerOptions, wellKnownTypeRegistry))!;
     }
 
     /// <summary>
@@ -61,7 +61,7 @@ public static partial class ActivityExecutionContextExtensions
     /// <exception cref="Exception">Thrown when the specified activity does not implement <see cref="IActivityWithResult"/>.</exception>
     public static void SetResult(this ActivityExecutionContext context, object? value)
     {
-        var activity = context.Activity as IActivityWithResult ?? throw new Exception($"Cannot set result on activity {context.Activity.Id} because it does not implement {nameof(IActivityWithResult)}.");
+        var activity = context.Activity as IActivityWithResult ?? throw new($"Cannot set result on activity {context.Activity.Id} because it does not implement {nameof(IActivityWithResult)}.");
         context.Set(activity.Result, value, "Result");
     }
 
@@ -79,7 +79,7 @@ public static partial class ActivityExecutionContextExtensions
     /// <param name="storageDriverType">The type of storage driver to use for the variable.</param>
     /// <param name="configure">A callback to configure the memory block.</param>
     /// <returns>The created <see cref="Variable"/>.</returns>
-    public static Variable CreateVariable(this ActivityExecutionContext context, string name, object? value, Type? storageDriverType = default, Action<MemoryBlock>? configure = default) =>
+    public static Variable CreateVariable(this ActivityExecutionContext context, string name, object? value, Type? storageDriverType = null, Action<MemoryBlock>? configure = null) =>
         context.ExpressionExecutionContext.CreateVariable(name, value, storageDriverType, configure);
 
     /// <summary>
@@ -90,7 +90,7 @@ public static partial class ActivityExecutionContextExtensions
     /// <param name="value">The value of the variable.</param>
     /// <param name="configure">A callback to configure the memory block.</param>
     /// <returns>The created <see cref="Variable"/>.</returns>
-    public static Variable SetVariable(this ActivityExecutionContext context, string name, object? value, Action<MemoryBlock>? configure = default) =>
+    public static Variable SetVariable(this ActivityExecutionContext context, string name, object? value, Action<MemoryBlock>? configure = null) =>
         context.ExpressionExecutionContext.SetVariable(name, value, configure);
 
     /// <summary>
diff --git a/src/modules/Elsa.Workflows.Core/Extensions/WorkflowExecutionContextExtensions.cs b/src/modules/Elsa.Workflows.Core/Extensions/WorkflowExecutionContextExtensions.cs
index 044abe9b2..6745c6004 100644
--- a/src/modules/Elsa.Workflows.Core/Extensions/WorkflowExecutionContextExtensions.cs
+++ b/src/modules/Elsa.Workflows.Core/Extensions/WorkflowExecutionContextExtensions.cs
@@ -88,7 +88,7 @@ public static class WorkflowExecutionContextExtensions
                 : WorkflowExecutionContext.Noop;
 
         // Store the bookmark to resume in the context.
-        workflowExecutionContext.ResumedBookmarkContext = new ResumedBookmarkContext(bookmark);
+        workflowExecutionContext.ResumedBookmarkContext = new(bookmark);
         logger.LogDebug("Scheduled activity {ActivityId} to resume from bookmark {BookmarkId}", bookmarkedActivity.Id, bookmark.Id);
 
         return workItem;
diff --git a/src/modules/Elsa.Workflows.Core/Models/Bookmark.cs b/src/modules/Elsa.Workflows.Core/Models/Bookmark.cs
index 9d062b336..e2ba868f8 100644
--- a/src/modules/Elsa.Workflows.Core/Models/Bookmark.cs
+++ b/src/modules/Elsa.Workflows.Core/Models/Bookmark.cs
@@ -26,13 +26,13 @@ public record Bookmark(
     string? ActivityInstanceId,
     DateTimeOffset CreatedAt,
     bool AutoBurn = true,
-    string? CallbackMethodName = default,
+    string? CallbackMethodName = null,
     bool AutoComplete = true,
-    IDictionary<string, string>? Metadata = default)
+    IDictionary<string, string>? Metadata = null)
 {
     /// <inheritdoc />
     [JsonConstructor]
-    public Bookmark() : this("", "", "",  null, "", "", "", default, default)
+    public Bookmark() : this("", "", "",  null, "", "", "", default, false)
     {
     }
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.Workflows.Runtime/Services/StimulusSender.cs b/src/modules/Elsa.Workflows.Runtime/Services/StimulusSender.cs
index 7ded4d3a3..039bb6b05 100644
--- a/src/modules/Elsa.Workflows.Runtime/Services/StimulusSender.cs
+++ b/src/modules/Elsa.Workflows.Runtime/Services/StimulusSender.cs
@@ -38,7 +38,7 @@ public class StimulusSender(
 
         var resumed = await ResumeExistingWorkflowsAsync(stimulusHash, metadata, cancellationToken);
         responses.AddRange(resumed);
-        return new SendStimulusResult(responses);
+        return new(responses);
     }
 
     private async Task<ICollection<RunWorkflowInstanceResponse>> TriggerNewWorkflowsAsync(string stimulusHash, StimulusMetadata? metadata = null, CancellationToken cancellationToken = default)
@@ -129,7 +129,7 @@ public class StimulusSender(
                 WorkflowInstanceId = workflowInstanceId,
                 BookmarkId = metadata?.BookmarkId,
                 StimulusHash = stimulusHash,
-                Options = new ResumeBookmarkOptions
+                Options = new()
                 {
                     Input = input,
                     Properties = properties