//get a list of credentials available to the session User
List listCredentials = port.listCredentials(0, Integer.MAX_VALUE, sessionId);
Credential currentCredential = null;
//Iterate over entire list
Iterator it1 = listCredentials.iterator();
while (currentCredential == null && it1.hasNext()) {
   Credential credential = it1.next();
   //Pervasive username/password credentials will have a type of "pervasiveSession"
   if (credential.getType().equals("pervasiveSession")) {
      //iterate through parameters -- the session id will be stored in a credential parameter
      Iterator it2 = credential.getParameters().getParameter().iterator();
      while (currentCredential == null && it2.hasNext()) {
         CredentialParameter cp = it2.next();
         //If the parameter key is sessionId and the value matches our
         //actual session Id then we've found our credential
         if ("sessionId".equals(cp.getKey()) && sessionId.equals(cp.getValue())) {
            currentCredential = credential;
         }
      }
   }
}
if (currentCredential == null) {
   throw new Exception("Failed to retrieve current credential");
}