Get Next Settlement Date

This function will take the date input and validate it as a settlement date but if it is invalid it will roll forward until a valid settlement date is determined.

Once the settlement date is valid (i.e. not in the past and a valid business date for the scheme) then it will derive the execution date and check if the execution date is in the past.

If the derived execution date is in the past then the settlement date will be revised to roll forward until the execution date is no longer in the past.

Once a valid execution date is established then it will return the derived Execution Date and revised Settlement Date