REST API return JSON object using factory and interface

I am trying to create a simple module to return JSON data, if i returned string or array it will return the targeted data, but i can’t return JSON object with key value

when i return the interface it will return error 500, the second time i refresh it will keep loading forever. so i have to restart apache to work.

so my code, first the product interface:

<?php
namespace MzTestApiToolApiData;

interface ProductInterface
{
    /**
     * @return int
     */
    public function getId();
    /**
     * @param int $id
     * @return $this
     */
    public function setId($id);

    /**
     * @return string
     */
    public function getName();
    /**
     * @param string $name
     * @return $this
     */
    public function setName($name);
}

the used model:

<?php

namespace MzTestApiToolModelData;

use MagentoFrameworkDataObject;
use MzTestApiToolApiDataProductInterface;

class Product extends DataObject implements ProductInterface
{
    /**
     * @inheritdoc
     */
    public function getId()
    {
        $this->getId();
        return $this->getData('id');
    }
    /**
     * @inheritdoc
     */
    public function setId($id)
    {
        return $this->setData('id', $id);
    }

    /**
     * @inheritdoc
     */
    public function getName()
    {
        return $this->getData('name');
    }
    /**
     * @inheritdoc
     */
    public function setName($name)
    {
        return $this->setData('name', $name);
    }
}

and in the method:

/**
 * @api
 * @param int $id
 * @return MzTestApiToolApiDataProductInterface
 * @throws NoSuchEntityException
 */
public function show($id)
{
    /** @var MzTestApiToolApiDataProductInterface $productInterface */
    $productInterface = $this->productInterfaceFactory->create();

    try {
        /** @var MagentoCatalogApiDataProductInterface $product */
        $product = $this->productRepository->getById($id);

        $productInterface->setId($product->getId());
        $productInterface->setSku($product->getSku());
        $productInterface->setName($product->getName());

        return $productInterface;
       
    } catch (NoSuchEntityException $th) {
        throw NoSuchEntityException::singleField('id', $id);
    }
}

Update:

ProductRepositoryInterface:

<?php
namespace MzTestApiToolApi;

use MagentoFrameworkExceptionNoSuchEntityException;

interface ProductRepositoryInterface
{
    /**
     * Undocumented function
     *
     * @api
     * @param int $id
     * @return MzTestApiToolApiDataProductInterface
     * @throws NoSuchEntityException
     */
    public function show($id);

}