feat: [ShoppingMerchantProducts] a new field base64_encoded_name is added to the Product message (#9089)

* feat: a new field `base64_encoded_name` is added to the `Product` message
feat: new fields - `base64_encoded_name` and `base64_encoded_product` added to the `ProductInput` message
docs: A comment for field `name` in message `.google.shopping.merchant.products.v1.ProductInput` is changed
docs: A comment for field `name` in message `.google.shopping.merchant.products.v1.Product` is changed

PiperOrigin-RevId: 896968813

Source-Link: googleapis/googleapis@2aba484

Source-Link: googleapis/googleapis-gen@820077f
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* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: gcf-owl-bot[bot]

ShoppingMerchantProducts/metadata/V1/Productinputs.php

@@ -52,10 +52,10 @@
  *                              MUST be used if any part of the product identifier (like `offer_id`)
  *                              contains characters such as `/`, `%`, or `~`.
  *                              *   Example: To represent the product ID `en~US~sku/123`, the
- *                              `{productInput}` segment must be the base64url encoding of this
- *                              string, which is `ZW5-VVMtc2t1LzEyMw`. The full resource name
+ *                              `{productInput}` segment must be the unpadded base64url encoding of
+ *                              this string, which is `ZW5-VVN-c2t1LzEyMw`. The full resource name
  *                              for the product would be
- *                              `accounts/123/productInputs/ZW5-VVMtc2t1LzEyMw`.
+ *                              `accounts/123/productInputs/ZW5-VVN-c2t1LzEyMw`.
  *
  *                              2.  **Plain Format**: The `{productInput}` segment is the tilde-separated
  *                              string
@@ -66,11 +66,7 @@
  *                              We recommend using the **Encoded Format** for all product IDs to ensure
  *                              correct parsing, especially those containing special characters. The
  *                              presence of tilde (`~`) characters in the `{productInput}` segment is used
- *                              to differentiate between the two formats.
- *
- *                              Note: For calls to the v1beta version, the plain format is
- *                              `channel~content_language~feed_label~offer_id`, for example:
- *                              `accounts/123/productinputs/online~en~US~sku123`. Please see
+ *                              to differentiate between the two formats. Please see
  *                              {@see ProductInputsServiceClient::productInputName()} for help formatting this field.
  * @param string $dataSource    The primary or supplemental data source from which the product
  *                              input should be deleted. Format:

ShoppingMerchantProducts/metadata/V1/Products.php

@@ -52,10 +52,10 @@
  *                              MUST be used if any part of the product identifier (like `offer_id`)
  *                              contains characters such as `/`, `%`, or `~`.
  *                              *   Example: To represent the product ID `en~US~sku/123`, the
- *                              `{product}` segment must be the base64url encoding of this
- *                              string, which is `ZW5-VVMtc2t1LzEyMw`. The full resource name
+ *                              `{product}` segment must be the unpadded base64url encoding of this
+ *                              string, which is `ZW5-VVN-c2t1LzEyMw`. The full resource name
  *                              for the product would be
- *                              `accounts/123/products/ZW5-VVMtc2t1LzEyMw`.
+ *                              `accounts/123/products/ZW5-VVN-c2t1LzEyMw`.
  *
  *                              2.  **Plain Format**: The `{product}` segment is the tilde-separated string
  *                              `content_language~feed_label~offer_id`. This format is suitable only