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Core annotations used for value types, used by Jackson data binding package.

There is a newer version: 2.18.1

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 POJO-valued property should be
 * serialized "unwrapped" -- that is, if it would be serialized as Object value,
 * its properties are instead included as properties of its containing
 * Object -- and deserialized reproducing "missing" structure.
 * 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 {@code @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.
 * When values are deserialized "wrapping" is applied so that serialized output can
 * be read back in.
 *
 * Also note that annotation only applies if:
 *

 * Value is serialized as an Object value (can not unwrap Array values using this
 *   mechanism)
 *   
 * Reading/writing is done using Jackson standard {@code BeanDeserializer} /
 *  {@code BeanSerializer}; or custom deserializer/serializer MUST explicitly
 *  support similar  operation.
 *   
 * Will not work with polymorphic type handling ("polymorphic deserialization")
 *   
 * 
 * Specifically note that this annotation WILL NOT WORK for structured types like
 * {@link java.util.Map}s or {@code JsonNode}s: for these types you will
 * instead need to use {@link JsonAnyGetter} and {@link JsonAnySetter} to achieve
 * similar operation.
 */
@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.
     */
    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.
     */
    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.
     */
    String suffix() default "";
}