Author: Shamim Rezaie
MDL-62059 mod_book: Implement null provider for mod_book
http://git.moodle.org/gw?p=moodle.git;a=commit;h=351bfbef06f5ef673974b3c8709be275a4354bc1
http://github.com/moodle/moodle/commit/351bfbef06f5ef673974b3c8709be275a4354bc1
+ 3.4 en [privacy:metadata,mod_book]