Magento2 – Associate Simple Product to Configurable Product

I need to import 40,000 product from xls so that reason I wrote an importer, I already did for magento 1.x but we switch our web site magento 2,
I can create simple and configurable product programatically but I cant associate simple product to configurable product, This is the best documentation I followed,

Programmatically create a configurable product and assign the simple product to configurable product in Magento2 product

But I stuck configurable product options always throw an error,

Call to a member function getId() on array in .../vendor/magento/module-configurable-product/Model/Plugin/AroundProductRepositorySave.php on line 109

Here is my code,

$configurableProductOptions = [
[
"attribute_id" =>  137,
"label" => 'size',
"position" => 0,
"values" => [
[
"value_index" =>  333,
],
[
"value_index" =>  334,
]
],
]
];

$product->setCanSaveConfigurableAttributes(true);
$product->setCanSaveCustomOptions(true);
$productExtensionFactory= $objectManager->create('\Magento\Catalog\Api\Data\ProductExtensionFactory');
$productExtension = $productExtensionFactory->create();
$productExtension->setConfigurableProductLinks($sipmle_product_ids);
$productExtension->setConfigurableProductOptions([
                                                $configurableProductOptions
                                                 ]);
$product->setExtensionAttributes($productExtension);
$productRepository = $objectManager->create(Magento\Catalog\Api\ProductRepositoryInterface::class);

$productRepository->save($product,true);

I m totaly sure something wrong in '$configurableProductOptions' tried almost everything but didnt succeed any ideas or anyone can share code to associate simple product as a configurable I can figured out from that code.