@Test
  public void testExtractResponseAndNotifyResponseHandler() {
    ResponseInfo responseInfo = new ResponseInfo(null, true);
    assertNull(RouterUtils.extractResponseAndNotifyResponseHandler(null, null, responseInfo, null, null));
  }
Test {@link RouterUtils#getAccountContainer(AccountService, short, short)}.
ambry-router/src/test/java/com/github/ambry/router/RouterUtilsTest.java