It's fine to break backwards compatibility when introducing an entirely new feature across a major version, actually. What's even the point of a major version bump?
In C#, the string `"""Hello world"` is invalid, but `@"""Hello world"` is, because double quotes are valid with verbatim string literals.
https://docs.oracle.com/en/java/javase/11/docs/api/java.base...
https://docs.oracle.com/en/java/javase/17/docs/api/java.base...