4.0.0

What's Changed

• Finalize open-source preparations
• Fixes duplicate http headers when more then 1 by @Sinmson and @julian-spierefka in #3
• Feature/generalize schema validation by @chrisingenhaag in #6

Full Changelog: https://github.com/telekom/pubsub-horizon-starlight/commits/4.0.0