Add a ResourceComparator to this Sort ResourceCollection.
If multiple ResourceComparators are added, they will be processed in LIFO order.
Parameters: c - the ResourceComparator to add.
Overrides the BaseResourceCollectionContainer version
to recurse on nested ResourceComparators.
Parameters: stk - the stack of data types to use (recursively). Parameters: p - the project to use to dereference the references. throws: BuildException - on error.