Well the answer depends on your definition of 'correct'. The
specification does not allow relationship mappings within an Embeddable
but EclipseLink does. As the XSD is restrictive in nature and the XSD is
defined by the specification the validation error results. Annotations
definitions are not as restrictive and as EclipseLink supports
relationship mappings within an Embeddable the annotations are
successfully processed. This is the best compromise between functionality
and compliance.
--Gordon