GetHandlerContractRefData ( parameter list ) : HandlerContractRefData
Returns relevant reference data in accordance with the parameter list. 
In addition to the current valid reference data the next valid reference data, if any, is returned.
Parameters:
All parameters are optional. The following parameters are supported:
- handlerCode : HandlerCode
 Returns only contract data for this handler. If not used, returns contract data for all relevant handlers.
- airlineIATAorICAO: AirlineIATAorICAO
 Returns only contract data for this airline. If not used, returns contract data for all relevant airlines.
- airportIATA: AirportIATA
 Returns only contract data for this airport. If not used, returns contract data for all relevant airports.
- onlyUpdatedAfter : DateTimeUTC
 Returns only reference data that is updated after "onlyUpdatedAfter".
Returns: