A simple Java implementation (no external libs) of Sipa's Python reference implementation test vectors for BIP340 Schnorr signatures for secp256k1. Sources: https://code.samourai.io/samouraidev/BIP340_Schnorr and https://github.com/unclebob/more-speech/tree/bdd2f32b37264f20bf6abb4887489e70d2b0fdf1