Creates a mapping/_SublayerExtension!SublayerExtension from the given properties.
The SublayerExtension properties.
OptionaldefaultSublayerType: stringOptionally specify the sublayerType to be created. (i.e. we are creating a child sublayer from a parent).
Creates new instances of mapping/support/SublayerExtensionFactory!SublayerExtensionFactory.