the POST message from CAS is not working in the previuos version of CAS. In cas-server-3.2.1-release the POST call is made and this filter works great to get the ticketid. I modify this lines to correct the filter
int start = line.indexOf("%3Csamlp%3ASessionIndex%3E");
int end = line.indexOf("%3C%2Fsamlp%3ASessionIndex%3E");
because I did not decode the line, but all work great.
Also I continue to working with sessionregistry and in the sessionController.registerSuccessfulAuthentication (Authentication request) I save to the sessionregistry some extra session information and request.getCredentials() in the case of CAS is the extra session information. with this filter i get the credential to logout directly obtaining SessionInformation and proceed to .expireNow();
thanks for all