code: public Iterable<Attribute> getAttributes() {
      Iterable<Attribute> attrs = getOwnAttributes();
      EntityType extend = getExtends();
      if (extend != null) {
        attrs = concat(attrs, extend.getAttributes());
      }
      return attrs;
    }
docs: Returns all attributes. In case of compound attributes (attributes consisting of atomic
  attributes) only the compound attribute is returned. This attribute can be used to retrieve
  parts of the compound attribute.
  
  <p>In case EntityType extends other EntityType then the attributes of this EntityType as well
  as its parent class are returned.
  
  @return entity attributes