package com.fasterxml.jackson.annotation;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

Annotation used to indicate that a property should be serialized
"unwrapped"; that is, if it would be serialized as JSON Object, its
properties are instead included as properties of its containing
Object. For example, consider case of POJO like:
 public class Parent {
   public int age;
   public Name name;
 }
 public class Name {
   public String first, last;
 }
  
which would normally be serialized as follows (assuming @JsonUnwrapped
had no effect):
 {
   "age" : 18,
   "name" : {
     "first" : "Joey",
     "last" : "Sixpack"
   }
 }

can be changed to this:
 {
   "age" : 18,
   "first" : "Joey",
   "last" : "Sixpack"
 }

by changing Parent class to:
 public class Parent {
   public int age;
   @JsonUnwrapped
   public Name name;
 }

Annotation can only be added to properties, and not classes, as it is contextual.

Also note that annotation only applies if

Value is serialized as JSON Object (can not unwrap JSON arrays using this
  mechanism)
  
Serialization is done using BeanSerializer, not a custom serializer
  
No type information is added; if type information needs to be added, structure can
  not be altered regardless of inclusion strategy; so annotation is basically ignored.
  

/**
 * Annotation used to indicate that a property should be serialized
 * "unwrapped"; that is, if it would be serialized as JSON Object, its
 * properties are instead included as properties of its containing
 * Object. For example, consider case of POJO like:
 * 
 *<pre>
 *  public class Parent {
 *    public int age;
 *    public Name name;
 *  }
 *  public class Name {
 *    public String first, last;
 *  }
 *</pre>  
 * which would normally be serialized as follows (assuming @JsonUnwrapped
 * had no effect):
 *<pre>
 *  {
 *    "age" : 18,
 *    "name" : {
 *      "first" : "Joey",
 *      "last" : "Sixpack"
 *    }
 *  }
 *</pre>
 * can be changed to this:
 *<pre>
 *  {
 *    "age" : 18,
 *    "first" : "Joey",
 *    "last" : "Sixpack"
 *  }
 *</pre>
 * by changing Parent class to:
 *<pre>
 *  public class Parent {
 *    public int age;
 *    &#064;JsonUnwrapped
 *    public Name name;
 *  }
 *</pre>
 * Annotation can only be added to properties, and not classes, as it is contextual.
 *<p>
 * Also note that annotation only applies if
 *<ul>
 * <li>Value is serialized as JSON Object (can not unwrap JSON arrays using this
 *   mechanism)
 *   </li>
 * <li>Serialization is done using <code>BeanSerializer</code>, not a custom serializer
 *   </li>
 * <li>No type information is added; if type information needs to be added, structure can
 *   not be altered regardless of inclusion strategy; so annotation is basically ignored.
 *   </li>
 * </ul>
 */
@Target({ElementType.ANNOTATION_TYPE, ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@JacksonAnnotation
public @interface JsonUnwrapped
{
    
Property that is usually only used when overriding (masking) annotations,
using mix-in annotations. Otherwise default value of 'true' is fine, and
value need not be explicitly included.
/**
     * Property that is usually only used when overriding (masking) annotations,
     * using mix-in annotations. Otherwise default value of 'true' is fine, and
     * value need not be explicitly included.
     */
    boolean enabled() default true;

    
Optional property that can be used to add prefix String to use in front
of names of properties that are unwrapped: this can be done for example to prevent
name collisions.
/**
     * Optional property that can be used to add prefix String to use in front
     * of names of properties that are unwrapped: this can be done for example to prevent
     * name collisions.
     */
    String prefix() default "";

    
Optional property that can be used to add suffix String to append at the end
of names of properties that are unwrapped: this can be done for example to prevent
name collisions.
/**
     * Optional property that can be used to add suffix String to append at the end
     * of names of properties that are unwrapped: this can be done for example to prevent
     * name collisions.
     */
    String suffix() default "";
}