Probably nothing more but a (minor) typo in the study guide. The Java API of LocalDateTime clearly mentions the toEpochSecond method (and just like the Java compiler, the Java API is always correct ). But in order to invoke this method, you'll need a zone offset as well (and null is not allowed). And for completeness: there's a LocalDateTime.ofEpochSecond(long epochSecond, int nanoOfSecond, ZoneOffset offset) as well. So it definitely is xxEpochSecond (and not xxEpochTime).
Agreed. I didn't reply to this one right away because I wanted to get to a computer and see how I didn't catch it when running the example. And I see why. It is a sidebar of an API method and not something I tried to run. Oops.
Thanks for reporting. Added to the errata. Have a cow for being the third person to report an error that isn't a simple typo.