DefiniteOrDeclined​(AngouriMath.​Entity,​AngouriMath.​Entity.​Variable,​AngouriMath.​Entity,​AngouriMath.​Entity,​System.​Boolean)

The definite integral, or the node as written where the integrand can jump and
the split at its jumps declined. Not null there: null hands the
expression to the expansion below, which distributes the integral into the
cases of a piecewise and under a provided whether or not their
conditions mention the integration variable -- and where they do, that is an
answer with the variable still in it. See BreakpointIntegration.