Added Interface-Message example.

src/samples/aspnet/Elsa.Samples.MassTransitRabbitMq/Controllers/TriggerMessageController.cs

@@ -1,3 +1,4 @@
+using System;
 using MassTransit;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Mvc;
@@ -33,5 +34,17 @@ namespace Elsa.Samples.MassTransitRabbitMq.Controllers
             await _publishEndpoint.Publish(message);
             return Ok();
         }
+
+        [Route("interface")]
+        [HttpPost]
+        public async Task<IActionResult> TriggerInterface()
+        {
+            var message = new
+            {
+                CorrelationId = Guid.Parse("e9ca46dd-36b9-4fc4-b7db-3bb7190e4488")
+            };
+            await _publishEndpoint.Publish<IInterfaceMessage>(message);
+            return Ok();
+        }
     }
 }

src/samples/aspnet/Elsa.Samples.MassTransitRabbitMq/Messages/IInterfaceMessage.cs

@@ -0,0 +1,12 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace Elsa.Samples.MassTransitRabbitMq.Messages
+{
+    public interface IInterfaceMessage
+    {
+        Guid CorrelationId { get; set; }
+    }
+}

src/samples/aspnet/Elsa.Samples.MassTransitRabbitMq/Startup.cs

@@ -23,6 +23,7 @@ namespace Elsa.Samples.MassTransitRabbitMq
                     // Add workflow consumer for message
                     x.AddConsumer(CreateWorkflowConsumer(typeof(FirstMessage)));
                     x.AddConsumer(CreateWorkflowConsumer(typeof(SecondMessage)));
+                    x.AddConsumer(CreateWorkflowConsumer(typeof(IInterfaceMessage)));
 
                     // Configure rabbitmq
                     x.UsingRabbitMq((ctx, cfg) =>
@@ -38,6 +39,7 @@ namespace Elsa.Samples.MassTransitRabbitMq
                     .AddConsoleActivities()
                     .AddMassTransitActivities()
                     .AddWorkflow<TestWorkflow>()
+                    .AddWorkflow<InterfaceTestWorkflow>()
                 );
         }
 

src/samples/aspnet/Elsa.Samples.MassTransitRabbitMq/Workflows/InterfaceTestWorkflow.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Elsa.Activities.Console;
+using Elsa.Activities.MassTransit;
+using Elsa.Builders;
+using Elsa.Samples.MassTransitRabbitMq.Messages;
+
+namespace Elsa.Samples.MassTransitRabbitMq.Workflows
+{
+    public class InterfaceTestWorkflow : IWorkflow
+    {
+        public void Build(IWorkflowBuilder builder)
+        {
+            builder
+                .ReceiveMassTransitMessage(
+                    activity => activity.Set(x => x.MessageType, x => typeof(IInterfaceMessage))
+                )
+                .WriteLine(context => $"Received interface message");
+        }
+    }
+}