Contact.java

package eu.anticom.model.opensearch;

import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import eu.anticom.serializer.ContactDeserializer;
import eu.anticom.serializer.ContactSerializer;

import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import java.io.UnsupportedEncodingException;

@JsonSerialize(using = ContactSerializer.class)
@JsonDeserialize(using = ContactDeserializer.class)
public class Contact extends InternetAddress {
    public Contact() {
        super();
    }

    public Contact(String address) throws AddressException {
        super(address);
    }

    public Contact(String address, boolean strict) throws AddressException {
        super(address, strict);
    }

    public Contact(String address, String personal) throws UnsupportedEncodingException {
        super(address, personal);
    }

    public Contact(String address, String personal, String charset) throws UnsupportedEncodingException {
        super(address, personal, charset);
    }
}

ContactSerializer.java

package eu.anticom.serializer;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.ser.std.StdSerializer;

import javax.mail.internet.InternetAddress;
import java.io.IOException;

public class ContactSerializer extends StdSerializer<InternetAddress> {
    public ContactSerializer() {
        this(null);
    }

    public ContactSerializer(Class<InternetAddress> t) {
        super(t);
    }

    @Override
    public void serialize(InternetAddress internetAddress, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
        jsonGenerator.writeStartObject();
        jsonGenerator.writeStringField("foo", internetAddress.toString());
        jsonGenerator.writeEndObject();
    }
}

issue.xml

<!-- expected -->
<MyRootNode>
  <Contact>foo@bar.baz</Contact>
</MyRootNode>

<!-- actual -->
<MyRootNode>
  <Contact>
    <foo>foo@bar.baz</foo>
  </Contact>
</MyRootNode>

MySchema.java

@JacksonXmlRootElement(localName = "MyRootNode", namespace = NS)
public class MySchema {
  public static final String NS = "http://a9.com/-/spec/opensearch/1.1/";
  
  @JacksonXmlProperty(localName = "Contact", namespace = NS)
  private Contact contact; 
}