When I was an undergrad student, we had an algorithms and data structures lecture based on the Java version of the book. We also got an archive with the samples

When I was an undergrad student, we had an algorithms and data structures lecture based on the Java version of the book. We also got an archive with the samples to work with that was IIRC GPL licensed. Did this repo contain the code or the entire book as well? In the former case, if I remember correctly, this DMCA claim would clearly be bogus. Yet another case where sending out DMCA claims having penalties for the sender if they are fraudulent, but putting a burden on the recipient who might suffer if they don't immediately act.