Update Quartz scheduler to only schedule once

Elsa.sln

@@ -168,7 +168,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "clients", "clients", "{8960
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Api.Client", "src\clients\Elsa.Api.Client\Elsa.Api.Client.csproj", "{1FCB2200-28B8-4703-8E89-73241AAED047}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Samples.QuartzIntegration", "src\samples\aspnet\Elsa.Samples.QuartzIntegration\Elsa.Samples.QuartzIntegration.csproj", "{B0312D9E-FA30-43E9-B666-40A8782D6E1C}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Samples.AspNet.QuartzIntegration", "src\samples\aspnet\Elsa.Samples.AspNet.QuartzIntegration\Elsa.Samples.AspNet.QuartzIntegration.csproj", "{B0312D9E-FA30-43E9-B666-40A8782D6E1C}"
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Samples.HangfireIntegration", "src\samples\aspnet\Elsa.Samples.HangfireIntegration\Elsa.Samples.HangfireIntegration.csproj", "{D2614FC7-102F-4F78-BB06-7C87304A10BA}"
 EndProject

src/modules/Elsa.Quartz/Services/QuartzWorkflowScheduler.cs

@@ -81,7 +81,10 @@ public class QuartzWorkflowScheduler : IWorkflowScheduler
     {
         var scheduler = await _schedulerFactory.GetScheduler(cancellationToken);
         var trigger = TriggerBuilder.Create().ForJob(RunWorkflowJob.JobKey).UsingJobData(CreateJobDataMap(request)).WithIdentity(taskName).WithCronSchedule(cronExpression).Build();
-        await scheduler.ScheduleJob(trigger, cancellationToken);
+        
+        if(!await scheduler.CheckExists(trigger.Key, cancellationToken)) 
+            await scheduler.ScheduleJob(trigger, cancellationToken);
+
     }
 
     /// <inheritdoc />

src/samples/aspnet/Elsa.Samples.AspNet.QuartzIntegration/Program.cs

@@ -44,6 +44,8 @@ builder.Services.AddElsa(elsa =>
     
     // Use default authentication (JWT).
     elsa.UseDefaultAuthentication();
+
+    elsa.AddWorkflowsFrom<Program>();
 });
 
 // Configure CORS to allow designer app hosted on a different origin to invoke the APIs.

src/samples/aspnet/Elsa.Samples.AspNet.QuartzIntegration/Workflows/HeartbeatWorkflow.cs

@@ -0,0 +1,38 @@
+using Elsa.Common.Contracts;
+using Elsa.Scheduling.Activities;
+using Elsa.Workflows.Core.Abstractions;
+using Elsa.Workflows.Core.Activities;
+using Elsa.Workflows.Core.Contracts;
+using JetBrains.Annotations;
+
+namespace Elsa.Samples.AspNet.QuartzIntegration.Workflows;
+
+[PublicAPI]
+public class HeartbeatWorkflow : WorkflowBase
+{
+    private readonly ISystemClock _systemClock;
+
+    public HeartbeatWorkflow(ISystemClock systemClock)
+    {
+        _systemClock = systemClock;
+    }
+    
+    protected override void Build(IWorkflowBuilder builder)
+    {
+        builder.Root = new Sequence
+        {
+            Activities =
+            {
+                new Cron
+                {
+                    CronExpression = new("*/1 * * * * ?"),
+                    CanStartWorkflow = true
+                },
+                new WriteLine
+                {
+                    Text = new($"Heartbeat workflow triggered at {_systemClock.UtcNow.LocalDateTime}")
+                }
+            }
+        };
+    }
+}