Method invoked before the store removes the given collection of cache nodes.
Original signature is '- (void)willRemoveCacheNodes:(NSSet *)cacheNodes'
Available in Mac OS X v10.5 and later.


- cacheNodes (NSSet)
- The set of cache nodes to remove.

- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)