```
@Retention(RUNTIME)
@Target(METHOD)
public @interface ImmutableValidator
```
Annotation defining which method is to be used to validate the bean when code generating immutable beans.
Each property in a bean can be independently validated. This annotation allows properties to be cross-checked at the end of the constructor.
The method must be a private void instance method and take no arguments. Private is necessary as it is called from the constructor. For example:
```
   @ImmutableValidator
   private void validate() {
     if (age != null && age < 0) {
       throw new IllegalArgumentException("Age must not be negative if specified")
     }
   }
 
```

Annotation Type ImmutableValidator