c# - ICollection<T> Why SerializationBinder is call on HashSet<T> but not on List<T> -

i have object :

public class mycollec {     public icollection<myobject> mycollection { get; set; }      public mycollec()     {         mycollection = new list<myobject>();     } } 

in webapi had serializationbinder, in webapiconfig :

jsonformatter.serializersettings.binder = new defaultserializationbinder(); 

when call controller return object structure this

{   "mycollection": [     {         ...     },     {         ...     }   ] } 

but if change constructor hashset

public mycollec() {     mycollection = new hashset<myobject>(); } 

the result of controller :

{   "mycollection": {     "$type": "system.collections.generic.hashset`1[[webapplication1.models.myobject, webapplication1]], system.core",     "$values": [             {                 ...             },             {                 ...             }         ]     } } 

i understand why ? difference induce behavior ?

is-it possible use hashset give same result list ?

edit :

@grundy comment :

typenamehandling property auto , doc: include .net type name when type of object being serialized not same declared type. seems hashset serialized not same declared type.

it's true, it's reason, why it's not true list ? type different of icollection hashset...

moreover, try change typenamehandling property there no option set $type on inherited objects...

http://www.newtonsoft.com/json/help/html/t_newtonsoft_json_typenamehandling.htm

thanks @grundy clue.

i keep

jsonformatter.serializersettings.typenamehandling = typenamehandling.auto; 

and had custom jsonconverter change serialization of hashset

public class hashsetarrayconverter : jsonconverter {     public override void writejson(jsonwriter writer, object value, jsonserializer serializer)     {         ienumerable collectionobj = (ienumerable)value;          writer.writestartobject();          foreach (object currobj in collectionobj)         {             serializer.serialize(writer, currobj);         }          writer.writeendobject();     }      public override object readjson(jsonreader reader, type objecttype, object existingvalue, jsonserializer serializer)     {         return serializer.deserialize(reader, objecttype);     }      public override bool canconvert(type objecttype)     {         var canconvert = isassignabletogenerictype(objecttype, typeof(hashset<>));         return canconvert;     }      private static bool isassignabletogenerictype(type giventype, type generictype)     {         var interfacetypes = giventype.getinterfaces();          if (interfacetypes.any(it => it.isgenerictype && it.getgenerictypedefinition() == generictype))         {             return true;         }          if (giventype.isgenerictype && giventype.getgenerictypedefinition() == generictype)             return true;          type basetype = giventype.basetype;         if (basetype == null) return false;          return isassignabletogenerictype(basetype, generictype);     } } 

and add in config :

jsonformatter.serializersettings.converters.add(new hashsetarrayconverter());