Convert a path to a cananonical form.
<p>
All instances of "." and ".." are factored out.
</p>
<p>
Null is returned if the path tries to .. above its root.
</p>
@param path the path to convert (expects URI/URL form, encoded, and with path separators '/')
@return the canonical path, or null if path traversal above root.
Convert a path to a cananonical form. <p> All instances of "." and ".." are factored out. </p> <p> Null is returned if the path tries to .. above its root. </p>
@param path the path to convert (expects URI/URL form, encoded, and with path separators '/') @return the canonical path, or null if path traversal above root.