o Coding Conventions
o Constness of methods
o Value printing
o Header in the root subdirectory

A 'collection' here is a class for which there is a TVirtualCollectionProxy. For example this applies to ATLAS' DataVector.

Make sure the consumer thread is properly notified by the main
thread both when there is a pending block and when the prefetching
is over.

(cherry picked from commit 234da8bfedce8661c2b8bc50f72632c240c4dfd8)