@Test
public void testAuthenticate_invalidEmail() {

  payload.setEmail("invalid@gmail.com");
  request.addHeader(EndpointsPeerAuthenticator.HEADER_PEER_AUTHORIZATION, FAKE_TOKEN);
  when(jwtAuthenticator.verifyToken(FAKE_TOKEN)).thenReturn(token);
  when(token.getPayload()).thenReturn(payload);
  assertFalse(authenticator.authenticate(request));
}