Major Description
WICKET-4626 WicketFilter unify the filterPath
Use of getter/setter internally to limit read/writes to filterPath
field location.
Removed lazy initialization code from main code path.
Provide a new method #canonicaliseFilterPath(String) to convert
"/wicket/" into "wicket/" as expected internally and maybe used by
unit tests to further validate correct values for filterPath.
Added unit test for this new method and use method in setter.