Unable to configure MassTransit send topology correlationId - rabbitmq

Question

I have two APIs one that sends a message and another with a consumer saga to consume that message. On the send side, my message model does not implement CorrelatedBy<> interface, but has a field I would like to use as a correlationId. As I understand from the documentation, that should be configured as follows.
GlobalTopology.Send.UseCorrelationId<SubmitOrder>(x => x.OrderId);
However, after setting that, I do not see a correlationId in my message once consumed by my consumer saga, it is an empty GUID.
I have also tried another approach outlined in the documentation, but that did not produce a correlationId in my saga either.
Bus.Factory.CreateUsingRabbitMQ(..., cfg =>
{
cfg.Send<OrderSubmitted>(x =>
{
x.UseCorrelationId(context => context.Message.OrderId);
});
});
Message Interface
public interface MyEvent {
Guid MyId { get; }
DateTime Timestamp { get; }
}
Registration
builder.AddMassTransit(x => {
x.Builder.RegisterBuildCallback(bc => {
var bus = bc.Resolve<IBusControl>();
bus.Start();
});
x.AddConsumers(Assembly.GetExecutingAssembly());
x.UsingRabbitMq((context, cfg) => {
cfg.Send<MyEvent>(x => {
x.UseCorrelationId(ctx => ctx.MyId);
});
cfg.Host(new Uri(Configuration["RabbitMqHost"]), host => {
host.Username(Configuration["RabbitMqUsername"]);
host.Password(Configuration["RabbitMqPassword"]);
});
cfg.ReceiveEndpoint(Configuration["RabbitMqQueueName"], ec => {
ec.ConfigureConsumers(context);
});
cfg.ConfigureEndpoints(context);
});
});
Where am I going wrong here? I would expect the value of MyId to be assigned to CorrelationId on send and show up in the consume context of my saga on the other end.
The workaround here is simple, follow convention and name my field CorrelationId, and everything works as expected.

Answer 1

Consumer sagas only correlate using the CorrelatedBy<Guid> interface, which must be on the message contract. They do not use the CorrelationId property on the ConsumeContext.