for https://gist.github.com/yfakariya/fb6d5c66fa4d8a82346b

MessagePackPolymorphicTypeStorage-code.java

import com.fasterxml.jackson.annotation.JsonValue;
import com.fasterxml.jackson.annotation.JsonCreator;

@MessagePackPolymorphicTypeStorage("csharp_types")
public class DictWithPersistentTypeInfo
{
    private final Map<String, Object> dict;
    
    @JsonCreator
    public MyDictWithPersistentTypeInfo(Map<String, Object> dict)
    {
        this.dict = dict;
    }

    @JsonValue
    public Map<String, Object> getDict()
    {
        return dict;
    }
}

public class MyClass
{
    private final String str1;
    private final String str2;

    ...
}

DictWithPersistentTypeInfo src = new DictWithPersistentTypeInfo(ImmutableMap.of(
    "myclass", MyClass.new("value1", "value2")
));

data = MessgePack.pack(my);
//
// If @MessagePackPolymorphicTypeStorage("csharp_types") is NOT set:
//     data = {"myclass": {"str1": "value1", "str2", "value2"}}
//
// If @MessagePackPolymorphicTypeStorage("csharp_types") is set:
//     data = {"myclass": {"str1": "value1", "str2", "value2"}, "csharp_types": {"myclass": "MyClass"}}
//

DictWithPersistentTypeInfo dst = new ObjectMapper().readValue(, DictWithPersistentTypeInfo.class);
//
// If @MessagePackPolymorphicTypeStorage("csharp_types") is NOT set:
//     dst.dict = {"myclass": {"str1": "value1", "str2", "value2"}}
//
// If @MessagePackPolymorphicTypeStorage("csharp_types") is set:
//     dst.dict = {"myclass": new MyClass("value1", "value2")}
//