Bug#1052581: libmatthew-java: FTBFS with OpenJDK 21 due to unsupported javac source/target level 7

[Vladimir Petko]

Dear Maintainers,

Would it be possible to consider a merge request[1] that addresses this
issue?

Best Regards,
 Vladimir.

[1]
https://salsa.debian.org/debian-iot-team/libmatthew-java/-/merge_requests/4