public function isExistClientProductCode($clientProductCod)
{
	$table = TableRegistry(..);
	$entity = $table->find()
					->where(['client_product_code' => $clientProductCod])
					->first();
	$return $entity();
}

public function create($entityProduct)
{
	$table = TableRegistry();
	$entity = new Entity();
	$entity = $entityProduct->product_uuid;
	$entity = $entityProduct->clientProductCode;
	$table->save($entity);
}

public function update($clientProductCode)
{
	$table = TableRegistry();
	$entity = $table->find()
					->where(['client_product_code' => $clientProductCod]);
	$entity->modified = null;
	$table->save();
}

$product = $product->findProductByClientCode();

if($product)
{
	if(isExistClientProductCode($clientProductCode)){
		domain->update($clientProductCode);
	}else{
		domain->create($product);
	}
}