You need to make several small, non-breaking updates to an existing API hosted in APIM. Requirements: do not disrupt existing callers, be able to roll back changes if needed, provide documentation for developers about the changes, and allow testing prior to publishing. What should you do?

Adding a new revision to the API in Azure API Management (APIM) is the correct approach because it directly addresses all requirements. Revisions allow you to make changes to an API without affecting existing consumers, as the current production revision remains active. This enables testing of the new revision before making it current, provides a clear history of changes for documentation, and allows for easy rollback by reverting to a previous revision. Header-based and query string-based versioning are used for managing different API versions (e.g., v1, v2) that might have breaking changes, not for non-breaking updates to a single API version. Creating and publishing a product bundles APIs for consumption but doesn't manage changes to an individual API. Configuring a custom policy applies specific logic to API requests/responses but isn't the mechanism for managing API definition updates with rollback capabilities.