Fix workflow memory issues

Elsa.sln

@@ -115,7 +115,7 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Testing.Shared", "src\
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Workflows.Sinks", "src\modules\Elsa.Workflows.Sinks\Elsa.Workflows.Sinks.csproj", "{7F1FDA45-C731-4DCC-BFF6-403D4B857A93}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Samples.WorkflowFunctions", "src\samples\console\Elsa.Samples.WorkflowFunctions\Elsa.Samples.WorkflowFunctions.csproj", "{4782CA82-83B0-437E-8C97-636BB8B402EA}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Samples.Console.WorkflowFunctions", "src\samples\console\Elsa.Samples.Console.WorkflowFunctions\Elsa.Samples.Console.WorkflowFunctions.csproj", "{4782CA82-83B0-437E-8C97-636BB8B402EA}"
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Samples.MyBackendApi", "src\samples\aspnet\Elsa.Samples.MyBackendApi\Elsa.Samples.MyBackendApi.csproj", "{1A37795B-EBAB-4A9F-8CF0-373DA3D4C64A}"
 EndProject

src/modules/Elsa.Workflows.Core/Abstractions/WorkflowBase.cs

@@ -69,7 +69,7 @@ public abstract class WorkflowBase<TResult> : WorkflowBase
     /// <inheritdoc />
     protected override ValueTask AfterBuildAsync(IWorkflowBuilder builder, CancellationToken cancellationToken = default)
     {
-        var variables = builder.Variables ?? new List<Variable>();
+        var variables = builder.Variables;
         
         if(!variables.Contains(Result))
            variables.Add(Result);

src/modules/Elsa.Workflows.Core/Activities/Composite.cs

@@ -48,8 +48,9 @@ public abstract class Composite : Activity, IVariableContainer
         ConfigureActivities(context);
         
         // Register variables.
-        context.ExpressionExecutionContext.Memory.Declare(Variables);
-        
+        foreach (var variable in Variables) 
+            variable.Set(context, variable.Value);
+
         await context.ScheduleActivityAsync(Root, OnRootCompletedAsync);
     }
 

src/modules/Elsa.Workflows.Core/Models/ActivityExecutionContext.cs

@@ -293,8 +293,8 @@ public class ActivityExecutionContext : IExecutionContext
 
     internal void IncrementExecutionCount() => _executionCount++;
 
-    private MemoryBlock? GetMemoryBlock(MemoryBlockReference locationBlockReference) =>
-        ExpressionExecutionContext.Memory.TryGetBlock(locationBlockReference.Id, out var memoryBlock)
-            ? memoryBlock
-            : ParentActivityExecutionContext?.GetMemoryBlock(locationBlockReference);
+    private MemoryBlock? GetMemoryBlock(MemoryBlockReference locationBlockReference)
+    {
+        return ExpressionExecutionContext.TryGetBlock(locationBlockReference, out var memoryBlock) ? memoryBlock : default;
+    }
 }

src/samples/console/Elsa.Samples.Console.WorkflowFunctions/Program.cs

@@ -1,4 +1,5 @@
 using Elsa.Extensions;
+using Elsa.Samples.Console.WorkflowFunctions.Workflows;
 using Elsa.Samples.WorkflowFunctions.Workflows;
 using Elsa.Workflows.Core.Contracts;
 using Microsoft.Extensions.DependencyInjection;

src/samples/console/Elsa.Samples.Console.WorkflowFunctions/Workflows/AddInputsWorkflow.cs

@@ -3,7 +3,7 @@ using Elsa.Workflows.Core.Abstractions;
 using Elsa.Workflows.Core.Activities;
 using Elsa.Workflows.Core.Contracts;
 
-namespace Elsa.Samples.WorkflowFunctions.Workflows;
+namespace Elsa.Samples.Console.WorkflowFunctions.Workflows;
 
 /// <summary>
 /// A simple workflow that takes two numbers as runtime workflow input and adds them together and returns the result as the workflow's result.

src/samples/console/Elsa.Samples.Console.WorkflowFunctions/Workflows/SumInputsWorkflow.cs

@@ -4,7 +4,7 @@ using Elsa.Workflows.Core.Activities;
 using Elsa.Workflows.Core.Contracts;
 using Elsa.Workflows.Core.Models;
 
-namespace Elsa.Samples.WorkflowFunctions.Workflows;
+namespace Elsa.Samples.Console.WorkflowFunctions.Workflows;
 
 /// <summary>
 /// A workflow that takes a list of numbers as runtime workflow input and returns the sum.
@@ -14,15 +14,12 @@ public class SumInputsWorkflow : WorkflowBase<float>
     protected override void Build(IWorkflowBuilder builder)
     {
         // Attach workflow variables.
-        var currentSum = new Variable<float>();
-        var currentValue = new Variable<float>();
-
-        builder.WithVariable(currentSum);
+        var currentSum = builder.WithVariable<float>();
+        var currentValue = builder.WithVariable<float>();
 
         // Define the sum logic.
         builder.Root = new Sequence
         {
-            Variables = { currentValue },
             Activities =
             {
                 new ForEach<float>(new Input<ICollection<float>>(context => context.GetInput<float[]>("numbers")!))