A regular expression to match an entire URI. If this object is
set to a zero-length string it is not used for matching with
the URI.
This object is mutually exclusive with patterns that match
specific fields from the URI e.g.,
cvSIPUriClassCfgUserIDPattern, or cvSIPUriClassCfgPhonePattern.
If more than one class matches a URI, the classes that matched
with the URI based on this pattern, are given the least
priority amongst matching classes.