Summary

This patch release fixes several issues and improves TypeScript typings. Notable changes include normalizing SVG attributes on root JSX elements, adding Atom/RSS mime mappings for SSG, making CORS origin optional, and propagating middleware response types into app.on overloads.

Key Points

• fix(jsx): normalize SVG attributes on the root element — prevents mismatched or non-normalized attribute names when rendering SVGs via JSX.
• fix(ssg): add atom+xml and rss+xml to defaultExtensionMap — ensures SSG recognizes and serves Atom/RSS feed files with correct MIME types.
• fix(cors): make origin optional in CORSOptions — allows omitting origin to rely on defaults or custom logic; no behavioral breaking change expected.
• fix(types): propagate middleware response types to app.on overloads — improves TypeScript inference so handler response types flow through middleware to route handlers.
• Contributors: small number of first-time contributors; patch release with no known breaking changes.

Upgrade guidance: install the patch release (4.12.17). Verify SVG rendering and any SSG feed endpoints, and recompile TypeScript to pick up improved typings.