final ComputationTarget target, final Set<ValueRequirement> desiredValues, final InstrumentDerivative derivative,
final FXMatrix fxMatrix) {
final ValueRequirement desiredValue = Iterables.getOnlyElement(desiredValues);
final ValueProperties constraints = desiredValue.getConstraints();
final Set<String> baseDayProperty = constraints.getValues(PROPERTY_BASE_DAYS);
final ValueProperties.Builder resultConstraints = constraints.copy();
final double baseDays;
if (baseDayProperty.size() == 1) {
baseDays = Double.parseDouble(Iterables.getOnlyElement(baseDayProperty));
resultConstraints.with(PROPERTY_BASE_DAYS, baseDayProperty);
} else {