The IDataProviderItemRendererMapper interface is the interface for beads
that know how to iterate through a dataProvider, generate item renderers,
and assign items from the dataProvider to those item renderers. In FlexJS,
a wide range of data providers are allowed, from simple Arrays and Vectors
on up to sophisticated data structures that dispatch change events.
Different IDataProviderItemRendererMapper implements are often required to
iterate through those different data structures.