http://github.com/FasterXML/jackson: Core annotations used for value types, used by Jackson data binding package. (FasterXML)
  • Tatu Saloranta 
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;


Marker annotation that can be used to define a logical "any setter" mutator -- either using non-static two-argument method (first argument name of property, second value to set) or a field (of type Map or POJO) - to be used as a "fallback" handler for all otherwise unrecognized properties found from JSON content. It is similar to javax.xml.bind.annotation.XmlAnyElement in behavior; and can only be used to denote a single property per type. 

If used, all otherwise unmapped key-value pairs from JSON Object values
are added using mutator.


NOTE: ability to annotated fields was added in version 2.8; earlier only
methods could be annotated.

/**
 * Marker annotation that can be used to define a logical "any setter" mutator --
 * either using non-static
 * two-argument method (first argument name of property, second value
 * to set) or a field (of type {@link java.util.Map} or POJO) -
 * to be used as a "fallback" handler
 * for all otherwise unrecognized properties found from JSON content.
 * It is similar to {@code javax.xml.bind.annotation.XmlAnyElement}
 * in behavior; and can only be used to denote a single property
 * per type.
 *<p>
 * If used, all otherwise unmapped key-value pairs from JSON Object values
 * are added using mutator.
 *<p>
 * NOTE: ability to annotated fields was added in version 2.8; earlier only
 * methods could be annotated.
 */
@Target({ElementType.ANNOTATION_TYPE, ElementType.METHOD, ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@JacksonAnnotation
public @interface JsonAnySetter
{
    
Optional argument that defines whether this annotation is active
or not. The only use for value 'false' if for overriding purposes.
Overriding may be necessary when used
with "mix-in annotations" (aka "annotation overrides").
For most cases, however, default value of "true" is just fine
and should be omitted.

Returns:True if annotation is enabled (normal case); false if it is to
  be ignored (only useful for mix-in annotations to "mask" annotation)
Since:2.9
/**
     * Optional argument that defines whether this annotation is active
     * or not. The only use for value 'false' if for overriding purposes.
     * Overriding may be necessary when used
     * with "mix-in annotations" (aka "annotation overrides").
     * For most cases, however, default value of "true" is just fine
     * and should be omitted.
     * 
     * @return True if annotation is enabled (normal case); false if it is to
     *   be ignored (only useful for mix-in annotations to "mask" annotation)
     *
     * @since 2.9
     */
    boolean enabled() default true;
}