@Test
public void testGetPeerAuthenticatorInstances_default() throws Exception {

  when(config.getPeerAuthenticators()).thenReturn(null);
  List<PeerAuthenticator> peerAuthenticators =
      Lists.newArrayList(peerAuth.getPeerAuthenticatorInstances());
  assertEquals(1, peerAuthenticators.size());
  assertTrue(peerAuthenticators.get(0) instanceof EndpointsPeerAuthenticator);
}