elsa-core/src/core/Elsa.Abstractions/Models/Activity.cs

namespace Elsa.Models
{
    public abstract class Activity : IActivity
    {
        public string Id { get; set; }
        public string Name => GetType().Name;
        public ActivityMetadata Metadata { get; set; } = new ActivityMetadata();
        public ActivityDescriptor Descriptor { get; set; }
    }
}