Trivial Description
FileAlterationObserver accepts a FileFilter, but there is no getter for it, which causes inconvenience when implementing a FileAlterationListener.
For example, when implementing FileAlterationListener.onStart(FileAlterationObserver), I wanted to get all existing files under FileAlterationObserver.getDirectory() that satisfies the FileFilter the user used to construct the observer, so that I can keep track of present states of the target files as well as their future states.
