title: Intershop EDL modelling - How to add dependency with on cascade delete
body: <p>We have some custom objects modelled through EDL which have foreign keys to system Intershop objects (ISPRODUCT and ISORDER). We need our objects to get deleted when referenced order or product is deleted. </p>
  
  <p>This is the extract from the EDL file:</p>
  
  <pre><code>/**
   * Relation to product PO (tariff item)
   */
  dependency tariff: ProductPO
  {
    foreign key(tariffID);
  }
  
  /*
   * Order relation
   */
  dependency order: OrderPO
  {
    foreign key(orderID);
  }
  </code></pre>
  
  <p>As I can see, it is possible to add delete actions on EDL relations but it is not possible to add delete actions on dependencies. </p>
  
  <p>What we are doing at the moment is modifying the statements in the generated dbconstraints.oracle.ddl files like this:</p>
  
  <pre><code>EXEC staging_ddl.add_constraint('A1APPLICATIONFORM', 'A1APPLICATIONFORM_CO_003', 'FOREIGN KEY (TARIFFID) REFERENCES PRODUCT (UUID) ON DELETE SET NULL INITIALLY DEFERRED DEFERRABLE DISABLE NOVALIDATE');
  EXEC staging_ddl.add_constraint('A1APPLICATIONFORM', 'A1APPLICATIONFORM_CO_004', 'FOREIGN KEY (ORDERID) REFERENCES ISORDER (UUID) ON DELETE CASCADE INITIALLY DEFERRED DEFERRABLE DISABLE NOVALIDATE');
  </code></pre>
  
  <p>But it is only the temporary workaround because these files will get overwritten each time we restart the code generator on the EDL.</p>
  
  <p>On relationship it is possible to define the on delete action like this:</p>
  
  <pre><code>relation promotionBenefitPOs : A1PromotionBenefitPO[0..n] inverse promotionPO implements promotionBenefits delete default;
  </code></pre>
  
  <p>Is it possible to achieve the same thing on the dependency with the system objects?</p>