--- a/Implab.ServiceHost/Unity/DefaultParameterElement.cs	Thu Apr 26 19:35:01 2018 +0300
+++ b/Implab.ServiceHost/Unity/DefaultParameterElement.cs	Fri Apr 27 04:47:52 2018 +0300
@@ -1,9 +1,12 @@
 namespace Implab.ServiceHost.Unity
 {
-    public class DefaultParameterElement : InjectionParameterElement {
-        internal override object Resolve(InjectionValueContext context) {
-            var type = context.ResolveType(TypeName);
-            return Safe.CreateDefaultValue(type);
+    public class DefaultParameterElement : InjectionParameterElement, ITextValue {
+        public string Value {
+            get { return null; }
+        }
+
+        internal override void Visit(InjectionValueBuilder builder) {
+            builder.Visit(this);
         }
     }
 }
\ No newline at end of file