I export an ExtendedGSSCredential with lifetime 5 hours to a byte array.    
Then I use createCredential method to create a new GSSCredential with lifetime 
1 hour (shown below). However, the lifetime of the newly created credential is 
still 5 hours. Seems that the lifetime argument does not have any effect.

ExtendedGSSManager manager =(ExtendedGSSManager)ExtendedGSSManager.getInstance
();
            
cred= manager.createCredential(
            buff,
            ExtendedGSSCredential.IMPEXP_OPAQUE,
            3600,
            null,
            GSSCredential.INITIATE_AND_ACCEPT);