toPacket method
toPacket converts the BleServiceData to a raw message following this structure: SERVICE_UUID:DATA
Implementation
String toPacket() {
String message = '${uuid.toRadixString(16).padLeft(4, '0').toUpperCase()}:';
message += data.map((e) => e.toRadixString(16).padLeft(2, '0')).join('').toUpperCase();
return message;
}