code: @Override
      public void close() throws Exception {
          unbindAll();
          initialContext.destroySubcontext("java:/comp/env/jdbc");
          initialContext.destroySubcontext("java:/comp/env");
          initialContext.destroySubcontext("java:/comp");
          initialContext.destroySubcontext("java:");
          initialContext.close();
      }
docs: Unbinds all data sources currently bound by this instance of this class.
  If successful, it then closes the {@link InitialContext}.
  @throws Exception if an error occurs during unbinding or closing.