extension attributes generate code error

[DartPeng2014]

Hi everyone,

I wrote a plugin followed with the "magento2 sample/sample-external-link" to add a "custom_test_attribute" on the product , here is "extension_attributes.xml" :

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Api/etc/extension_attributes.xsd">
    <extension_attributes for="Magento\Catalog\Api\Data\ProductInterface">
        <attribute code="custom_test_attribute" type="string" />
    </extension_attributes>
</config>

di.xml and plugin code:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Catalog\Api\ProductRepositoryInterface">
        <plugin name="ProductExtensionAttributeOperations" type="zasi\ExtensionRest\plugin\AddReviewAttributes"  disabled="false"/>
    </type>
</config>

<?php

namespace zasi\ExtensionRest\plugin;


use Magento\Catalog\Api\Data\ProductExtensionInterface;
use Magento\Catalog\Api\Data\ProductInterface;
use Magento\Catalog\Api\Data\ProductExtensionFactory;

class AddReviewAttributes
{

        private $extensionFactory;

        public function __construct(ProductExtensionFactory $extensionFactory)
        {   
            $this->extensionFactory = $extensionFactory;
        }

        public function afterGetList
        (
            \Magento\Catalog\Api\ProductRepositoryInterface $subject,
            \Magento\Framework\Api\SearchResults $searchResult
        ) {
            /** @var \Magento\Catalog\Api\Data\ProductInterface $product */
            foreach ($searchResult->getItems() as $product) {
                $this->addExternalLinksToProduct($product);
            }

            return $searchResult;
        }

        public function afterGet
        (
            \Magento\Catalog\Api\ProductRepositoryInterface $subject,
            \Magento\Catalog\Api\Data\ProductInterface $product
        ) {
            $this->addExternalLinksToProduct($product);
            return $product;
        }


        private function addExternalLinksToProduct(\Magento\Catalog\Api\Data\ProductInterface $product)
        {
            $extensionAttributes = $product->getExtensionAttributes();

            if (empty($extensionAttributes)) {
                $extensionAttributes = $this->productExtensionFactory->create();
            }
            
            $extensionAttributes->setCustomTestAttribute('test');
            $product->setExtensionAttributes($extensionAttributes);
            return $this;
        }

}

When I use postman to get the response via "rest/V1/products" router, I got an error , it said : 

Fatal Error: 'Uncaught TypeError: Argument 1 passed to Magento\\Catalog\\Api\\Data\\ProductExtension::setCustomTestAttribute() must be an instance of number, string given, 

I found the methods genrated by magento incorrectly:

ProductExtensionInterface.php:

<?php
namespace Magento\Catalog\Api\Data;

/**
 * ExtensionInterface class for @see \Magento\Catalog\Api\Data\ProductInterface
 */
interface ProductExtensionInterface extends \Magento\Framework\Api\ExtensionAttributesInterface
{
 ........
    /**
     * @return number|null
     */
    public function getCustomTestAttribute();

    /**
     * @param number $customTestAttribute
     * @return $this
     */
    public function setCustomTestAttribute(\number $customTestAttribute);
}

the setCustomTestAttribute paramters is "\number $customTestAttribute" , I have to correct it manually.

This problem stuck me a whole day , can you guys help me to fix it? what's wrong with my codes?

(magento CE 2.3.3 , Apache/2.4.6 (CentOS) OpenSSL/1.0.2k-fips PHP/7.3.12)

Thanks you verrrrrry much!!

[DartPeng2014 · Accepted solution]

update my problem:

I add a new extension attribute in the xml file , but the it does not appear in generate code.

I remembered that at first I set the 'custom_test_attribute' type is 'number' , so I guest is that the code generator use some cache template

I disable all caches and upgrade again . it works