There is currently no good way to get all information about a given extension
from an X509CRL or X509Certificate. It is possible to get a list of all
critical extension OIDs, and check to see if your extension is among them (to
see if it is critical). It is possible to get an extension value (which is usually useless without an instantiating class). But there is no one method
that easily obtains all information about the extension.