The continuous callback
Describes the common interface of callbacks for simplex and barrier optimizers.
The second special callback class is IloCplex::ContinuousCallbackI (IloCplex.ContinuousCallback in
the Java API or CPLEX.ContinuousCallback in
the .NET API or callbacks.ContinuousCallback in
the Python API). If you create a continuous callback and use it with
an IloCplex object, it will be used for
both the barrier and the simplex callback. In other words, implementing
and using one Continuous callback is equivalent to writing and using
these two callbacks independently.