CAS provides the following components to accommodate different legacy authentication needs for backwards compatibility:
###`LegacyAuthenticationHandlerAdapter`
Adapts a CAS 3.x `AuthenticationHandler` onto a CAS 4.x `AuthenticationHandler`. If the supplied legacy authentication handler supports `NamedAuthenticationHandler`, then its defined name will be used to identify the handler. Otherwise, the name of the class itself will be used.
###`CredentialsAdapter`
Interface to be implemented by adapters to determine how credentials need be converted over to CAS 4.
####`UsernamePasswordCredentialsAdapter`
Adapts and converts a CAS 4 username/password credential into a CAS 3.x username/password credential.