Wraps the value found at a path in a list. Many systems expect a list of items even when there is only one, while a source might send a single object instead. Use this to find the value at the path you give and, if it is not already a list, place it inside a one-item list so the rest of your mapping can always loop over it. A value that is already a list is left as it is. You can optionally keep going into nested data and convert that too.