jacksonpolymorphicdeserialization https://stackoverflow.com/questions/28993035/jacksonpolymorphicdeserialization-jsonmappingexception

OptionOne.java

import com.fasterxml.jackson.annotation.*;
import com.fasterxml.jackson.databind.*;
import lombok.Data;
import lombok.ToString;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.Objects;

/**
 * Created by varren on 17.10.17.
 */
public class OptionOne {
    public static void main(String[] args) throws IOException {
        ObjectMapper mapper = new ObjectMapper();
        test(mapper);
    }

    private static void test(ObjectMapper mapper) throws IOException {
        ComboParameter p = new ComboParameter();
        p.setRegEx("*");
        p.setValues(Arrays.asList("1","2","3"));
        A a = new A();
        a.setOtherField("other");
        a.setParameter(p);
        String json = mapper.writeValueAsString(a);
        System.out.println("From: "+ json);
        A aNew = mapper.readValue(json,A.class);
        System.out.println("To  : "+ aNew);
        System.out.println("From == To: "+ Objects.equals(a, aNew));
    }
    @Data
    @JsonSubTypes({
            @JsonSubTypes.Type(value = IntegerParameter.class, name = "integerParam"),
            @JsonSubTypes.Type(value = ComboParameter.class, name = "comboParam")
    })
    @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.WRAPPER_OBJECT)
    public static abstract class Parameter {
        String regEx;
    }

    @Data
    @ToString(callSuper=true)
    @JsonTypeName("integerParam")
    public static class IntegerParameter extends Parameter {}

    @Data
    @ToString(callSuper=true)
    @JsonTypeName("comboParam")
    public static class ComboParameter extends Parameter {
        List<String> values;
    }

    @Data
    public static class A {
        String otherField;

        @JsonIgnore
        Parameter parameter;


        private static ObjectMapper mapper = new ObjectMapper();

        @JsonAnyGetter
        private Map<String, Object> parameterAsMap(){
            return mapper.convertValue(parameter, Map.class);
        }

        @JsonAnySetter
        private void parameterFromMap(String key, JsonNode value)  {
            try {
                parameter =  mapper.readValue(String.format("{\"%s\":%s}", key,value),
                        Parameter.class);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

}

OptionTwo.java

import com.fasterxml.jackson.annotation.*;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.TreeNode;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.module.SimpleModule;
import lombok.Data;
import lombok.ToString;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.Objects;

/**
 * Created by varren on 17.10.17.
 */
public class OptionTwo {
    public static void main(String[] args) throws IOException {
        ObjectMapper mapper = new ObjectMapper();

        SimpleModule module = new SimpleModule();

        module.addSerializer(A.class, new ASerializer());
        module.addDeserializer(A.class, new ADeserializer());

        mapper.registerModule(module);

        mapper.disable(SerializationFeature.FAIL_ON_UNWRAPPED_TYPE_IDENTIFIERS);
        test(mapper);
    }

    private static void test(ObjectMapper mapper) throws IOException {
        ComboParameter p = new ComboParameter();
        p.setRegEx("*");
        p.setValues(Arrays.asList("1", "2", "3"));
        A a = new A();
        a.setOtherField("other");
        a.setParameter(p);
        String json = mapper.writeValueAsString(a);
        System.out.println("From: " + json);
        A aNew = mapper.readValue(json, A.class);
        System.out.println("To  : " + aNew);
        System.out.println("From == To: " + Objects.equals(a, aNew));
    }

    @Data
    @JsonSubTypes({
            @JsonSubTypes.Type(value = IntegerParameter.class, name = "integerParam"),
            @JsonSubTypes.Type(value = ComboParameter.class, name = "comboParam")
    })
    @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.WRAPPER_OBJECT)
    public static abstract class Parameter {
        String regEx;
    }

    @Data
    @ToString(callSuper = true)
    @JsonTypeName("integerParam")
    public static class IntegerParameter extends Parameter {

    }

    @Data
    @ToString(callSuper = true)
    @JsonTypeName("comboParam")
    public static class ComboParameter extends Parameter {
        List<String> values;
    }

    @Data
    public static class A {
        String otherField;
        Parameter parameter;
    }


    public static class ASerializer extends JsonSerializer<A> {
        private static ObjectMapper m = new ObjectMapper();

        @Override
        public void serialize(A value, JsonGenerator gen,
                              SerializerProvider serializers) throws IOException {
            Map defaults = m.convertValue(value, Map.class);
            Map params = m.convertValue(value.getParameter(), Map.class);
            defaults.putAll(params);
            gen.writeObject(defaults);
        }

    }


    public static class ADeserializer extends JsonDeserializer<A> {
        private static ObjectMapper m = new ObjectMapper();
        private static String[] subtipes = {"integerParam", "comboParam"};

        public ADeserializer() {
            m.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
        }

        @Override
        public A deserialize(JsonParser p, DeserializationContext ctxt)
                throws IOException {

            TreeNode node = m.readTree(p);

            A a = m.convertValue(node, A.class);

            // hardcoded , probably can be done dynamically
            for (String key : subtipes) {
                TreeNode value = node.get(key);
                if (value != null) {
                    String json = String.format("{\"%s\":%s}", key, value);
                    a.setParameter(m.readValue(json, Parameter.class));
                    break;
                }
            }

            return a;
        }
    }
}