You are going to want to do any work on ACCUMULO-2255 (or the sub-tickets) in a branch. I would actively discourage committers from applying refactorings in master before 1.6.0 is released. Merging changes through 1.4, 1.5 and 1.6 is hard enough as it is.
Environment.getAuthorizations is in the public API, but since it has been deprecated for one release (the upcoming 1.6 release), it could be removed. There's been some (offline) discussion of being less aggressive removing deprecated APIs. I would leave it out for now.