About Question enthuware.ocpjp.v7.2.1724 :

[bptoth]

In the explanation part it might worth to mention that here in fact the overloaded version of Collections.sort() is used, which gets a Comparator as a second parameter (in this case value null, that would mean natural ordering). The one-argument version of sort() would not even compile with an Object[] array converted to List

[admin]

You are right. The explanation has been updated.
thank you for your feedback!
Paul.