@Nullable
	private TreeItem<String> getItem(@Nonnull ConfigContainer container, boolean createIfMissing) {
		TreeItem<String> currentItem = root;
		String currentPackage = null;
		String[] packages = getGroupPackages(container);
		for (String packageName : packages) {
			if (currentPackage == null)
				currentPackage = packageName;
			else
				currentPackage += PACKAGE_SPLIT + packageName;

			// Get or setup tree item.
			TreeItem<String> child = getChildTreeItemByName(currentItem, currentPackage);
			if (child == null) {
				if (createIfMissing) {
					// No existing tree item, create one.
					child = new TreeItem<>(currentPackage);
					child.setExpanded(true);

					// Insert child in sorted order.
					List<String> childrenNames = currentItem.getChildren().stream()
							.map(TreeItem::getValue)
							.toList();
					int insertIndex = Lists.sortedInsertIndex(childrenNames, currentPackage);
					currentItem.getChildren().add(insertIndex, child);
				} else {
					// Exit, cannot find item
					return null;
				}
			}
			currentItem = child;
		}
		return currentItem;
	}
@param container
		Container to get item of.
@param createIfMissing
		Flag to create item if it does not exist.

@return Tree item if it exists. Otherwise {@code null}.
recaf-ui/src/main/java/software/coley/recaf/ui/pane/ConfigPane.java