void checkCommonGetHeadHeaders(HttpHeaders receivedHeaders) {
    assertNotNull("No Date header", receivedHeaders.get(HttpHeaderNames.DATE));
    assertNotNull("No Last-Modified header", receivedHeaders.get(HttpHeaderNames.LAST_MODIFIED));
  }
Checks headers that are common to HEAD and GET.
@param receivedHeaders the {@link HttpHeaders} that were received.
ambry-frontend/src/integration-test/java/com/github/ambry/frontend/FrontendIntegrationTestBase.java