@Override protected void check( final MappedClass mc, final MappedField mf, final Set<ConstraintViolation> ve) { if (mf.hasAnnotation(Reference.class)) { final Class realType = (mf.isSingleValue()) ? mf.getType() : mf.getSubClass(); if (realType == null) { throw new MappingException("Type is null for this MappedField: " + mf); } if ((!realType.isInterface() && mc.getMapper().getMappedClass(realType).getIdField() == null)) { ve.add( new ConstraintViolation( Level.FATAL, mc, mf, getClass(), mf.getFullName() + " is annotated as a @" + Reference.class.getSimpleName() + " but the " + mf.getType().getName() + " class is missing the @" + Id.class.getSimpleName() + " annotation")); } } }