You have one comment for them. I think this is enough, unless you have no idea about what they're doing.

// Signatures with special case values for r and s (such as 0 and 1). // Such values often uncover implementation errors.

Of course! Code should be concise without being cleverly brief, and it should be clear with its intentions. I write software for business though that references back to requirements. In my case, I'm not explaining a bunch of odd values that look arbitrary. I'm indicating a reason for writing something the manner I'm which I wrote, so if it needs to be modified, they're not opening 5 tabs or searching through pages of documents to make sure things are still compatible. Or worse, modifying without caring and updating the test to assertNotNull(obj).