Instead of parametrising an instance of org.apache.cxf.policy.PolicyInterceptorProviderImpl
we use this class to reduce the impact of changes to the addressing metadata namespace
(only need to update Metadataconstants, otherwise cfg file fragement also).
Helper method to determine if an MAPs Action is empty (a null action
is considered empty, whereas a zero length action suppresses
the propogation of the Action property).
This object contains factory methods for each
Java content interface and Java element interface
generated in the org.w3._2006._05.addressing.wsdl package.