I would probably have titled Chapter 12 "New I/O and Security" and briefly overviewed each API. I couldn't have gone into too much depth because of the print-on-demand limit of 1000 pages. For this reason, Appendixes A through D couldn't be included in the book but can be downloaded freely from Apress's book site and my tutortutor.ca site.
For New I/O, I would have touched on buffers, channels, selectors, regular expressions, and charsets -- regular expressions should be covered in an NIO chapter because they were included in the JSR that introduced NIO. I would also have introduced NIO.2 and overviewed some of its features.
Regarding security, there are two aspects to consider: platform security (e.g., security manager, access controller, sandbox) and cryptography. I would have overviewed each of these two aspects in the second half of that chapter.
All the best.
subject: What would you have added to Beginning Java 7?