code: public void renew(GSSCredential newCred, boolean limitedDelegation)
          throws GramException, GSSException {
          Gram.renew(this, newCred, limitedDelegation);
      }
docs: Requests that the job's delegated credentials be renewed/refreshed.
  
  @param newCred The credentials to use in the delegation process
  @param limitedDelegation Whether to use limited or full delegated proxy
  @throws GramException if a connection/comunication error occurs or if
  delegation failed
  @throws GSSException if a GSSAPI error occurs