AbstractContainerImpl extends AbstractComponentImpl implements Container { @Override @JsonIgnore @NotNull public List<ListItem> getItems() { if (items == null) { items = readItems().stream().map(i -> (ListItem) i).collect(Collectors.toList()); } return items; }  @Override @JsonIgnore @NotNull List<ListItem> getItems(); @Nullable @Override String getBackgroundStyle(); @NotNull @Override String getExportedType(); @NotNull @Override Map<String, ? extends ComponentExporter> getExportedItems(); @NotNull @Override String[] getExportedItemsOrder();  }
@Test public void testEmptyContainer() { Container container = new ContainerImpl(); List<ListItem> items = container.getItems(); assertEquals(0, items.size()); }