An Adobe Commerce developer adds a new extension attribute to add an array of values...

When adding extension attributes in Adobe Commerce, it's essential to reference the correct interface in the extension_attributes.xml file. Extension attributes in Magento are used to add custom data fields to existing entities, and these should extend the core entity interfaces, not their repositories.

In this case:

The developer needs to reference Magento\Sales\Api\Data\InvoiceInterface, which represents the data structure of invoices, rather than any repository or incorrect interfaces.

The extension_attributes.xml should specify the data interface (e.g., Magento\Sales\Api\Data\InvoiceInterface) to ensure the extension attribute is correctly applied to the invoice entity and is accessible when fetching invoices through APIs.

Correct XML format:

Additional Resources:

Adobe Commerce Developer Guide: Using Extension Attributes

Extension Attributes XML Reference