Fixes nested array for used products cache key

[michaellehmkuhl]

Description (*)

When $requiredAttributeIds is passed as an array, it was previously being added to the $keyParts array directly, which resulted in a nested array. When this nested array is passed to getUsedProductsCacheKey(), the implode() in that function throws a notice and produces a cache key that contains the non-unique string "Array" as a part. This can result in caching errors where simple children of configurable products are concerned (e.g., swatches).

Fixed Issues (if relevant)

N/A - no existing issue found

Manual testing scenarios (*)

Call Magento\ConfigurableProduct\Model\Product\Type\Configurable::getUsedProducts($product, $requiredAttributeIds = null) passing different $requiredAttributeIds arrays of attribute codes and confirm that Magento\ConfigurableProduct\Model\Product\Type\Configurable::getUsedProducts() returns unique cache keys for each.

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[magento-cicd2]

All committers have signed the CLA.

[magento-engcom-team]

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[magento-engcom-team]

Hi @VladimirZaets, thank you for the review.
ENGCOM-4506 has been created to process this Pull Request

[magento-engcom-team]

@michaellehmkuhl thank you for contributing. Please accept Community Contributors team invitation here to gain extended permissions for this repository.

[soleksii]

✔️ QA Passed

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