Place the .class folder in a subdirectory of your project with the correct package structure. Refresh the project so that eclipse picks up the new directory.

Java 24 adds several new features to the language, such as the availability of the Stream Gatherers API and Class-File API, ...

Java 23, now generally available, includes previews of module import declarations, stream gatherers, structured concurrency, scoped values, and a class-file API. And much more.