Parameters (as Magnolia's configuration nodes):
- allow: comma separated lists of allowed extensions.
- deny: comma separated lists of denied extensions.
Returns:
false
if the extension is not a valid mimetype (as configured in config:/server/MIMEMapping.
false
if the allow list exists, but the extension is not in the allow list.
false
if the deny list exists and the extension is in the deny list.
true
in all other cases.
Typed to Object, as it can vote on both a passed String,
or the current MgnlContext.webContext if any.