Product specifications are not getting created if not available on the portal

Issue

• When specifications are not available on the portal. It's giving 500 Internal Server Error in the response body while creating the product via headless API.
• Steps to reproduce:
  1. Create a product by using POST /v1.0/products (Request is attached).
  2. Below is the Request for product specifications:( Material and dimensions are already created/available on the portal)
  

  "productSpecifications": [
      {
        "specificationKey": "material",
        "value": {
          "en_US": "Rubber"
        }
      },
  {
  "specificationKey": "dimensions",
        "value": {
          "en_US": "22mm"
        }
  }
    ]

  3. In Request, change the 'material' and 'dimensions' with anything which is not available on the portal. E.g. with 'brand' and 'size'.
  4. Execute it and check it's giving a 500 code response.
  Expected Behavior: The product must be created with specifications.
  Actual Behavior: The product is not created and it's giving a 500 response code.

Environment

• Liferay DXP 7.3
• Commerce 3.0

Resolution

• To create a specification for a product the 'label' value must be provided. Because it is the title of the specification.
• Below changes must be done to create a product.
  

  "productSpecifications": [
      {
        "specificationKey": "test",
        "label": {
          "en_US": "Test Label"
        },
        "value": {
          "en_US": "Rubber"
        }
      },
  {
  "specificationKey": "test",
      "label": {
          "en_US": "Brand"
        },
        "value": {
          "en_US": "Apple"
        }
  }
    ]

Additional Information

• Unable to add Products with Specifications via headless API