@Inject BinarySearchSolver solver;

...

Function<Double, Affordability> affordabilityFn ...; // our mapping function that takes a number and returns an affordability

Function<Affordability, Boolean> manageableTargetTest = affordability -> affordability.getOrdinal() <= MANAGEABLE.getOrdinal();

double maxManageablePrice = solver.solveForMaxValuePassingTargetTest(
	lowerBound,
	upperBound,
	tolerance, // how close our upper and lower bounds should be to stop searching
	affordabilityFn,
	manageableTargetTest,
	maxSearchIterations);