Reads the <saml:Advice> element.
Assembly: System.IdentityModel (in System.IdentityModel.dll)
The Advice element has an extensibility point to allow XML elements from non-SAML 2.0 namespaces to be included. By default, because the Advice may be ignored without affecting the semantics of the assertion, any such elements are ignored. To handle the processing of those elements, override this method.