By default when a Resource is found, the path of the resolved resource is
compared to ensure it's under the input location where it was found.
However sometimes that may not be the case, e.g. when
resolves public URLs of links it contains, the CSS file is the location
and the resources being resolved are css files, images, fonts and others
located in adjacent or parent directories.
This property allows configuring a complete list of locations under
which resources must be so that if a resource is not under the location
relative to which it was found, this list may be checked as well.
Perform additional checks on a resolved resource beyond checking whether the
resources exists and is readable. The default implementation also verifies
the resource is either under the location relative to which it was found or
is under one of the allowed locations.
resource - the resource to check
location - the location relative to which the resource was found
"true" if resource is in a valid location, "false" otherwise.