This is the correct implementation of @JsonTypeInfo and related annotations when performing polymorphic JSON deserialization on an embedded interface property. It also illustrates the use of an Enum as a type name. See StackOverflow question: http://stackoverflow.com/questions/21485923/java-jackson-polymorphic-json-deserialization-of-an-object-w…

Asset.java

public class Asset {
    private AssetType type;
    
    @JsonTypeInfo(
            use = JsonTypeInfo.Id.NAME,
            include = JsonTypeInfo.As.EXTERNAL_PROPERTY,
            property = "type"
    )
    @JsonSubTypes({
            @JsonSubTypes.Type(value = ImageAssetProperties.class, name = "image"),
            @JsonSubTypes.Type(value = DocumentAssetProperties.class, name = "document")
    })
    private AssetProperties properties;

    public String getType() {
        return type.toString();
    }
    
    @JsonProperty("type")
    public void setType(String type) {
        this.type = AssetType.fromString(type);
    }
    
    @JsonIgnore
    public void setType(AssetType type) {
        this.type = type;
    }

    public AssetProperties getProperties() {
        return properties;
    }
    
    public void setProperties(AssetProperties properties) {
        this.properties = properties;
    }
}

AssetProperties.java

public interface AssetProperties {
    String getSource();
    AssetProperties setSource(String source);
    String getProxy();
    AssetProperties setProxy(String proxy);
}

AssetType.java

public enum AssetType {
    IMAGE("image"),
    DOCUMENT("document");
    
    private String string;

    AssetType(String string) {
        this.string = string;
    }

    public static AssetType fromString(String string) {
        // Enum.valueOf() method is case sensitive; this method is not.
        if (string != null)
            for (AssetType assetType : AssetType.values())
                if (string.equalsIgnoreCase(assetType.toString()))
                    return assetType;
        throw new IllegalArgumentException(String.format("%s is not a valid AssetType.", string);
    }

    public String toString() {
        return this.string;
    }
}

DocumentAssetProperties.java

public class DocumentAssetProperties implements AssetProperties {
    private String source;
    private String proxy;

    public String getSource() {
        return source;
    }
    
    public DocumentAssetProperties setSource(String source) {
        this.source = source;
        return this;
    }

    public String getProxy() {
        return proxy;
    }
    
    public DocumentAssetProperties setProxy(String proxy) {
        this.proxy = proxy;
        return this;
    }
}

ImageAssetProperties.java

public class ImageAssetProperties implements AssetProperties {
    private String source;
    private String proxy;
    private Integer height;
    private Integer width;

    public String getSource() {
        return source;
    }
    
    public ImageAssetProperties setSource(String source) {
        this.source = source;
        return this;
    }

    public String getProxy() {
        return proxy;
    }
    
    public ImageAssetProperties setProxy(String proxy) {
        this.proxy = proxy;
        return this;
    }
    
    public Integer getHeight() {
        return height;
    }

    public ImageAssetProperties setHeight(Integer height) {
        this.height = height;
        return this;
    }

    public Integer getWidth() {
        return width;
    }

    public ImageAssetProperties setWidth(Integer width) {
        this.width = width;
        return this;
    }
}

PolymorphicDeserializationTests.java

public class PolymorphicDeserializationTests {
 
    @Test
    public void deserializeJsonSucceeds() {
        Asset asset = deserializeJson("{ \"type\": \"document\", \"properties\": { \"source\": \"foo\", \"proxy\": \"bar\" } }");
        Assert.assertTrue(asset.getProperties() instanceof DocumentAssetProperties);
    }
 
    public Asset deserializeJson(String json) {
        ObjectMapper mapper = new ObjectMapper();
        try {
            return mapper.readValue(json, Asset.class);
        }
        catch(IOException e) {
            Assert.fail("Could not deserialize JSON.", e);
        }
        return null;
    }
}

I've tried to use this approach and unfortunately this does not work for me. So now instead of having 1 instance there are two. One precedes the object and after that follows it. When I'm trying to de-serialize the first object causes a problem like:
"Missing property 'name' for external type id"

I also had some difficulty getting this to work. I was receiving the following exception

com.fasterxml.jackson.databind.JsonMappingException: Missing property 'content' 
  for external type id 'contentType

I ended up having to add the @JsonTypeId annotation to the type field referenced as the EXTERNAL_PROPERTY

public interface Content {
}

public class Post implements Content {
  public String content = "bar";
}

public class Foo {

  @JsonTypeInfo(use = JsonTypeInfo.Id.NAME,
                include = JsonTypeInfo.As.EXTERNAL_PROPERTY,
                property = "contentType")
  @JsonSubTypes({
    @JsonSubTypes.Type(value = Post.class, name = "post")
  })
  public Content content;

  @JsonTypeId
  public ContentType contentType;

  public enum ContentType {
    "post"
  }
}

I believe this Stack Exchange question is a similar issue.

http://stackoverflow.com/questions/28089484/deserialization-with-jsonsubtypes-for-no-value-missing-property-error/30473550#30473550

Any idea how you'd do this without using an external property?

I've got a setup that looks like this:

1st request

{
  "foo": "bar",
  "a": {
     "spam": "lots of spam",
  }
}

2nd request

{
  "foo": "bar",
  "b": {
     "eggs": "lots of eggs",
  }
}

public interface AB { }

@JsonTypeName("b")
public class A implements AB {
  @JsonProperty("spam")
  public String spam:
}

@JsonTypeName("b")
public class B implements AB {
  @JsonProperty("eggs")
  public String eggs;
}

public class Container {
  @JsonProperty("foo")
  public String foo;

  @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.WRAPPER_OBJECT)
  @JsonSubTypes({@JsonSubTypes.Type(value = A.class), @JsonSubTypes.Type(value = B.class)})
  public AB ab;
}

However my tests trying to deserialize a container end with Unrecognized field "a", not marked as ignorable (2 known properties: "foo", "ab") ... :\

I'm trying serialize java object to JSON by skipping the interface class name in the serialized string. Is there a way we can do it?

The details are at: https://stackoverflow.com/questions/45270140/how-to-serialize-java-to-json-without-including-the-interface-name-in-the-serial