package foo

import com.fasterxml.jackson.annotation.JsonIdentityInfo;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonSubTypes;
import com.fasterxml.jackson.annotation.JsonSubTypes.Type;
import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.fasterxml.jackson.annotation.JsonTypeInfo.Id;
import com.fasterxml.jackson.annotation.ObjectIdGenerators;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.yaml.YAMLFactory;
import java.util.List;
import org.junit.Test;

public class JacksonYamlTest {
    
    static class Container {
        @JsonProperty
        List<Base> list;
    }
    
    @JsonTypeInfo(use = Id.NAME)
    @JsonSubTypes({@Type(name="Derived", value=Derived.class)})
    @JsonIdentityInfo(generator = ObjectIdGenerators.StringIdGenerator.class)
    static class Base {
        
    }
    
    static class Derived extends Base {
        @JsonProperty
        String a;
    }
    
    @Test
    public void typedObjectIdTest() throws Exception {
        
        String yaml = "list:\n" +
                      "    - !Derived &id1\n" +
                      "        a: foo";
        
        ObjectMapper mapper = new ObjectMapper (new YAMLFactory());
        Container container = mapper.readValue (yaml, Container.class);
        
        System.out.println (((Derived)container.list.get(0)).a);
    }
}

com.fasterxml.jackson.databind.JsonMappingException: Already had POJO for id (java.lang.String) [[ObjectId: key=id1, type=com.fasterxml.jackson.annotation.ObjectIdGenerators$StringIdGenerator, scope=NONE]] (through reference chain: JacksonYamlTest$Container["list"]->java.util.ArrayList[0])
	at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:397)
	at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:368)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer._deserializeWithObjectId(CollectionDeserializer.java:406)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:277)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:249)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:26)
	at com.fasterxml.jackson.databind.deser.impl.FieldProperty.deserializeAndSet(FieldProperty.java:138)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:293)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:156)
	at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4526)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3468)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3436)
	at JacksonYamlTest.typedObjectIdTest(JacksonYamlTest.java:41)