OIC Gen 3 and "Design-time built-in APIs"?

The Oracle Integration 3 eligibility checker is suddenly giving me the warning "DT factory api's should be accessed using Oauth in Oracle Integration 3. Change Basic auth to Oauth for the connections invoking DT Api's." The Integrations Prechecks documentation also now says "If your instance includes integrations that use a REST connection with basic authentication to access design-time built-in APIs, you must change them to use OAuth."

My prior understanding was that only the REST APIs for managing the OIC platform needed to be switched to OAuth, and that our integrations themselves could continue using Basic authentication. Is that no longer true? What exactly is a "factory API" and a "design-time built-in API"?