Builds the platform fee from the updated cost schedule.
If the trip´s autoGeneratePlatformFees flag is true, the platform fee for each item of the cost schedule is calculated again,
otherwise, the platform fees are taken from the original platform fee, calculating the fees for any new cost schedule items.
Builds the platform fee from the updated cost schedule. If the trip´s
autoGeneratePlatformFeesflag is true, the platform fee for each item of the cost schedule is calculated again, otherwise, the platform fees are taken from the original platform fee, calculating the fees for any new cost schedule items.