Returns the CollectionBackend associated with source, or
null if there is no CollectionBackend associated
with source.
An Source is associated with an CollectionBackend if the Source has an SourceCollection extension, or if it is a hierarchical descendant of another Source which has an SourceCollection extension.
The returned CollectionBackend is referenced for thread-safety. Unreference the CollectionBackend with unref when finished with it.
| this | |
| source |
an Source |
|
the CollectionBackend for |