/**
* @api
* @param int $productId
* @return array
*/
public function addProduct($productId){
    $userType = $this->userContext->getUserType();
    $product = null;
    $customerId = null;

    if($this->isLoggedIn()){
        $customerId = $this->userContext->getUserId();
        //$this->item->setCustomerId($customerId);
    }
    $product = $this->productRepository->getById($productId,false,1);
    $this->catalogProductCompareList->addProduct($product);
    $viewData = [
        'product_id' => $productId,
        'customer_id' => $customerId,
        'visitor_id' => $this->visitor->getId()
    ];
    $this->compareFactory->create()->setData($viewData)->save();
    $collection = $this->catalogProductCompareList->getItemCollection();
    $a = array();
    //foreach($collection as $item){
        array_push($a, $collection->getData());
    //}
    return $a;