In general, when they show you a simple code fragment, you are often expected to presume the appropriate import statements are present but omitted from the fragment.
A nice clue they often provide is that line numbers begin with say, 3 or 5 or 6 or 8 or something...
If they show for instance, a package declaration, or any imports, that question is presumably showing you "all the code" and it is reasonable to presume you are supposed to notice the missing import.
In this case, going as far as showing you one import statement, I believe this is intended to represent a full class definition with all provided imports, in the default (unnamed) package, making your complaint correct.
Likely when either of the authors gets up enough time, they will pop in here and "batch process" threads here relating to their books.
Sometimes we go off on tangents or give confusing advice, however, normally I think the regular folk around here do a pretty good job of welcoming errata posters, and confirming or denying their suspicions / agreeing or disagreeing whether we think something should count as an actual error.
So you probably don't need to do anything further but hurry up and wait. In the meantime, according to the clues I gave I would definitely consider that an error. They show at least one import, and a common mistake beginners make is to think importing a package imports its sub-packages. It does not, or there is no such thing as sub-packages, depending on who you talk to.