This converts a IATA/ATA Cargo-IMP FWB/15 message to its FWB/14 equivalent.
The FWB/15 message is parsed using a aParse generated parser and converted using a visitor that implements the following conversion rules.
Replace the Standard Message Identification FWB/15 with FWB/14.
Remove any Volume Detail or Density Group on the AWB Consignment Details line.
Otherwise the FWB/14 is identical to the FWB/15.