code: @Override
      protected void closeSession(String message) {
          GSSContext ctx = (GSSContext) getSession().getAttribute(GSS_CONTEXT);
          if (ctx != null) {
              try {
                  ctx.dispose();
              } catch (GSSException e) {
                  e.printStackTrace();
                  super.closeSession(message, e);
                  return;
              }
          }
          super.closeSession(message);
      }
docs: Closes the session. If any {@link GSSContext} is present in the session
  then it is closed.
  
  @param message the error message