DataPump acts both as a DataSink and a DataSource. DataDump takes the Data
it receives as a DataSink and exposes that as a DataSource. This is useful
as a way to combine multiple Data streams (with the caveat that this
DataDump might be returning Data from the previous integrator step).
Returns a DataProcessor that casts the data that will be given
to this DataSink to a form that it can accept. Returns null if the
Data is acceptable without casting. Otherwise object that is pushing
the Data into this DataSink is responsible for filtering the Data through
the returned DataTransformer.