As of June 12th, 2017, Shopify will be including a new “locale” key-value pair in Hosted Payment SDK requests.
When signing the request, you will need to ensure your integration does not rely on specific fields. Instead, the message being signed should be a string of all key-value pairs that start with x_ prefix, sorted alphabetically, and concatenated without separators. If your integration’s signing mechanism already follows this strategy, you won’t need to make any changes now or in the future.
You can find help on developing a signing mechanism here ›
Making this change ensures your integration is resilient to any future addition/removal of request fields by Shopify, and is highly recommended.