For extra credit, you can run the JUnit tests in the example project. There are three tests, and they demonstrate some basic features on the JJWT library. The first test shows the happy path, creating and successfully decoding a valid JWT. The second test shows how the JJWT library will fail when you attempt to decode a totally bogus string as a JWT. The last test shows how a tampered-with JJWT will cause the decodeJWT() method to throw a SignatureException.