Why does @Documented annotation have runtime retention?

Question

As I know, @Documented annotation is used only by javadoc generator to generate javadocs from sources. So retention type should be SOURCE, but it's RUNTIME. Why?

@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.ANNOTATION_TYPE)
public @interface Documented {
}

Answer 1

IMO that does not explain why @Documented needs runtime retention

Yes, it does. Lets say I ship a jar file without the sources. A user can build a proper javadoc using only information from classfiles the the reason that classfile have proper annotations is becase they are RetentionPolicy.RUNTIME.