UNDERTOW-272 Validate non canonical name for FileResource

I've added same validation used in master for 1.0.x branch.
Directories represented with symbolic links can be missed in 1.0.x without this validation.
I'm reviewing 1.1.x validation
https://github.com/undertow-io/undertow/blob/master/core/src/main/java/io/undertow/server/handlers/resource/FileResourceManager.java#L90
at it seems correct.
As a caseSensitive can be handle first in the file.exist() validation, and the equalsIgnoreCase() used for these special validations.
Perhaps you are thinking in some potential dangerous scenario ?
Thanks,
Lucas