Javadoc
A processor with no inputs cannot be driven by the supply of data tokens
as it has nowhere to receive such tokens. This method allows a processor
to fire on an empty input set, in this case the owning process identifier
must be passed explicitly to the processor. Internally this pushes a
single empty job event into the dispatch queue, bypassing the iteration
logic (which is entirely predicated on the existence of input ports).
Callers must ensure that an appropriate process identifier is specified,
the behaviour on missing or duplicate process identifiers is not defined.