Create a heterogeneous list, where the user can choose an arbitrary number of arbitrary items with a common describable base type, and configure them independently. Each describable class needs to provide a config.jelly.
The submission can be data-bound into List<T> where T is the common base type for the describable instances (Entry in the snippet below).
See the documentation of repeatableHeteroProperty for a complete list of attributes and what they do.

Configure me!