unpack method
Implementation
@override
void unpack(IsoComponent<Object> component, IsoBuffer buffer) {
final Uint8List hexChars = buffer.getBytes(length * 2);
final Uint8List raw = IsoUtil.hex2byte(String.fromCharCodes(hexChars));
(component as IsoBitMapField).value = IsoUtil.byte2BitSetFromBytes(raw, 0, length << 3);
}