Discussed with Gunnar a bit on IRC. Some thoughts:
{code}
/**
* Marks a custom annotation as a defining an identifier generator.
* <p/>
* Custom annotations must have retention policy {@link RetentionPolicy#RUNTIME}.
*/
public interface CustomIdentifierGeneratorAnnotationMarker {
Class<? extends IdentifierGeneratorBuilder> builder();
}
public interface IdentifierGeneratorBuilder {
public IdentifierGenerator getIdentifierGenerator(Annotation customAnnotation, ... );
}
{code}
So for example:
{code}
public class MyUuidGenerator implements IdentifierGenerator {
...
}
public class MyUuidGeneratorBuilder implements IdentifierGeneratorBuilder {
public IdentifierGenerator getIdentifierGenerator(Annotation customAnnotation, ... ) {
return new MyUuidGenerator();
}
}
@CustomIdentifierGeneratorAnnotationMarker( builder = MyUuidGeneratorBuilder.class )
@Retention( RetentionPolicy.RUNTIME )
public @interface UUID {
}
{code}
Then a user would be able to use this custom annotation/generator like:
{code}
@Id
@GeneratedValue
@UUID
private UUID id;
{code}
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