code: public Iterable<Attribute> getAtomicAttributes() {
      Iterable<Attribute> atomicAttrs = getOwnAtomicAttributes();
      EntityType extend = getExtends();
      if (extend != null) {
        atomicAttrs = concat(atomicAttrs, extend.getAtomicAttributes());
      }
      return atomicAttrs;
    }
docs: Returns all atomic attributes. In case of compound attributes (attributes consisting of atomic
  attributes) only the descendant atomic attributes are returned. The compound attribute itself
  is not returned.
  
  <p>In case EntityType extends other EntityType then the attributes of this EntityType as well
  as its parent class are returned.
  
  @return atomic attributes