@VisibleForTesting
  static boolean areProxyPropertiesSet(String protocol) {
    return PROXY_PROPERTIES.stream()
        .anyMatch(property -> System.getProperty(protocol + "." + property) != null);
  }
@Test
  public void testAreProxyPropertiesSet_httpUserSet() {
    System.setProperty("http.proxyUser", "user");
    Assert.assertTrue(MavenSettingsProxyProvider.areProxyPropertiesSet("http"));
    Assert.assertFalse(MavenSettingsProxyProvider.areProxyPropertiesSet("https"));
  }