@Test
public void testGetUserAgentValue() {

  Map<String, String> headersMap =
      ImmutableMap.of(
          "Custom-Header", "CustomHeader", "User-Agent", "this is me", "accept", "Accept");
  assertEquals("this is me", HttpHeadersUtils.getUserAgentValue(headersMap));
  headersMap = ImmutableMap.of("Custom-Header", "CustomHeader", "accept", "Accept");
  assertNull(HttpHeadersUtils.getUserAgentValue(headersMap));
}