Unable to use custom XmlParser for WebAppContext / MetaData descriptor parsing

[joakime]

Jetty version(s)
12.1.5

Enhancement Description

If we want to use a custom XmlParser with our own set of configurations / attributes (things like the various validation modes, external entities control, custom catalogs, custom namespace handling, etc) we cannot, as the descriptors use a static method in WebDescriptor to access that XmlParser.

Can we have a central location to provide our custom XmlParser that is then used by the WebAppContext / MetaData / Descriptors?