### Question:
SiteMapConfigurationsContainerImpl extends ConfigurationFactoryContainerBase<SiteMapConfiguration> implements SiteMapConfigurationsContainer { @Override public Collection<SiteMapConfiguration> getAll() { final HashSet<SiteMapConfiguration> result = new HashSet<>(items); result.add(defaultSiteMapExtractor); return result; }  @Override Collection<SiteMapConfiguration> getAll();  }### Answer:
@Test public void testEverything() { Collection<SiteMapConfiguration> all = model.getAll(); assertEquals(1, all.size()); assertTrue(model.add(configuration)); all = model.getAll(); assertTrue(all.contains(configuration)); assertTrue(model.remove(configuration)); all = model.getAll(); assertEquals(1, all.size()); }