question: private Annotation [ ] extract ( Annotation label ) throws Exception { Class union = label . annotationType ( ) ; Method [ ] list = union . getDeclaredMethods ( ) ; if ( list . length != 1 ) { throw new UnionException ( "Annotation '%s' is not a valid union for %s" , label , type ) ; } Method method = list [ 0 ] ; Object value = method . invoke ( label ) ; return ( Annotation [ ] ) value ; }
target:  This is used to extract the individual annotations associated with the union annotation provided. If the annotation does not represent a union then this will return null.