In 2.6.0, we added the setParameter newCollectionsUsePowerOf2Sizes, which defaults to true.
As of 2.8.0 newCollectionsUsePowerOf2Sizes is now ignored by the server. If users are setting this value at startup or runtime, we should add a warning which points to a dochub link describing the change and describes the noPadding option required to get the old behavior with MMAPv1. See also: DOCS-4327.

We should also warn when users set the option usePowerOf2Sizes on a per collection basis from the shell.