gistfile1.txt

        protected override void MapType(TypeDefinition type)
        {
            base.MapType(type);

            MapDerivedTypes(type);
            MapInterfaceImplementors(type);
        }

        void MapDerivedTypes(TypeDefinition type)
        {
            if (!type.IsClass)
                return;

            var bases = Annotations.GetClassHierarchy(type);
            if (bases == null)
                return;

            foreach (var @base in bases)
            {
                Annotations.AddDerived(@base, type);
            }
        }

        void MapInterfaceImplementors(TypeDefinition type)
        {
            MapInterfaceImplementors(type, type);
            var bases = Annotations.GetClassHierarchy(type);
            if (bases == null)
                return;

            foreach (var @base in bases)
                MapInterfaceImplementors(type, @base);
        }

        void MapInterfaceImplementors(TypeDefinition originalType, TypeDefinition currentType)
        {
            foreach (var @iface in currentType.Interfaces)
            {
                var resolvedInterface = @iface.InterfaceType.Resolve();
                if (resolvedInterface == null)
                    continue;
                Annotations.AddImplementor(resolvedInterface, originalType, @iface);
            }
        }
        
        
and over in our UnityAnnotationStore

readonly Dictionary<TypeDefinition, List<InterfaceImplementorInformation>> implementorsOfInterfaces = new Dictionary<TypeDefinition, List<InterfaceImplementorInformation>>();
        readonly Dictionary<TypeDefinition, List<TypeDefinition>> derivedTypes = new Dictionary<TypeDefinition, List<TypeDefinition>>();
        
        
        
                public System.Collections.ObjectModel.ReadOnlyCollection<InterfaceImplementorInformation> GetImplementors(TypeDefinition @interface)
        {
            if (implementorsOfInterfaces.TryGetValue(@interface, out List<InterfaceImplementorInformation> implementors))
                return implementors.AsReadOnly();

            return null;
        }

        public System.Collections.ObjectModel.ReadOnlyCollection<TypeDefinition> GetDerived(TypeDefinition type)
        {
            if (derivedTypes.TryGetValue(type, out List<TypeDefinition> derived))
                return derived.AsReadOnly();

            return null;
        }

        public void AddDerived(TypeDefinition type, TypeDefinition derived)
        {
            if (!derivedTypes.TryGetValue(type, out List<TypeDefinition> items))
                derivedTypes[type] = items = new List<TypeDefinition>();

            items.Add(derived);
        }

        public void AddImplementor(TypeDefinition @interface, TypeDefinition implementor, InterfaceImplementation interfaceImplementation)
        {
            if (!implementorsOfInterfaces.TryGetValue(@interface, out List<InterfaceImplementorInformation> items))
                implementorsOfInterfaces[@interface] = items = new List<InterfaceImplementorInformation>();

            items.Add(new InterfaceImplementorInformation(implementor, interfaceImplementation));
        }