A naming provider InitialContextFactory implementation that combines
two Naming services to allow for delegation of lookups from one to the
other. The default naming service is specified via the standard
Context.PROVIDER_URL property while the secondary service is specified
using an org.jboss.naming.provider.url2 property. An example of where
this would be used is to bridge between the local JNDI service and the
HAJNDI service. Lookups into the local JNDI service that fail would then
try the HAJNDI service.