/**
  * Add foreign key reference.
  *
  * @param \MwbExporter\Model\ForeignKey $foreign
  */
 public function markAsForeignReference(ForeignKey $foreign)
 {
     $this->foreigns[$foreign->getId()] = $foreign;
 }
 /**
  * Inject relation.
  *
  * @param \MwbExporter\Model\ForeignKey $foreignKey
  */
 public function injectRelation(ForeignKey $foreignKey)
 {
     foreach ($this->relations as $_relation) {
         if ($_relation->getId() === $foreignKey->getId()) {
             return;
         }
     }
     $this->relations[] = $foreignKey;
 }