make NgTankSystem input parameter optional

VECTO/Input Files/Vehicle.vb

@@ -664,7 +664,7 @@ Public Class Vehicle
 	End Get
 	End Property
 
-	Public ReadOnly Property TankSystem As TankSystem Implements IVehicleDeclarationInputData.TankSystem
+	Public ReadOnly Property TankSystem As TankSystem? Implements IVehicleDeclarationInputData.TankSystem
 	get
 			Return DeclarationData.Vehicle.TankSystemDefault
 	End Get
@@ -729,4 +729,6 @@ Public Class Vehicle
 			Return DeclarationData.Vehicle.ADAS.PredictiveCruiseControlDefault
 	End Get
 	End Property
+
+
 End Class

VectoCommon/VectoCommon/InputData/DeclarationInputData.cs

@@ -142,7 +142,7 @@ namespace TUGraz.VectoCommon.InputData
 
 		bool SleeperCab { get; }
 
-		TankSystem TankSystem { get; }
+		TankSystem? TankSystem { get; }
 
 		IAdvancedDriverAssistantSystemDeclarationInputData ADAS { get; }
 

VectoCore/VectoCore/InputData/FileIO/JSON/JSONComponentInputData.cs

@@ -304,7 +304,7 @@ namespace TUGraz.VectoCore.InputData.FileIO.JSON
 
 		public bool VocationalVehicle { get { return DeclarationData.Vehicle.VocationalVehicleDefault; } }
 		public bool SleeperCab { get { return DeclarationData.Vehicle.SleeperCabDefault; } }
-		public TankSystem TankSystem { get { return DeclarationData.Vehicle.TankSystemDefault; } }
+		public TankSystem? TankSystem { get { return DeclarationData.Vehicle.TankSystemDefault; } }
 		public IAdvancedDriverAssistantSystemDeclarationInputData ADAS { get { return this; } }
 		public bool ZeroEmissionVehicle { get { return DeclarationData.Vehicle.ZeroEmissionVehicleDefault; } }
 		public bool HybridElectricHDV { get { return DeclarationData.Vehicle.HybridElectricHDVDefault; } }

VectoCore/VectoCore/InputData/FileIO/JSON/JSONVehicleData.cs

@@ -260,7 +260,7 @@ namespace TUGraz.VectoCore.InputData.FileIO.JSON
 
 		public bool SleeperCab { get { return DeclarationData.Vehicle.SleeperCabDefault; } }
 
-		public TankSystem TankSystem { get { return DeclarationData.Vehicle.TankSystemDefault; } }
+		public TankSystem? TankSystem { get { return DeclarationData.Vehicle.TankSystemDefault; } }
 		public IAdvancedDriverAssistantSystemDeclarationInputData ADAS { get { return this; } }
 
 		public bool ZeroEmissionVehicle { get { return DeclarationData.Vehicle.ZeroEmissionVehicleDefault; } }

VectoCore/VectoCore/InputData/FileIO/XML/Declaration/XMLDeclarationVehicleDataProvider.cs

@@ -269,10 +269,10 @@ namespace TUGraz.VectoCore.InputData.FileIO.XML.Declaration
 				? XmlConvert.ToBoolean(GetElementValue(XMLNames.Vehicle_SleeperCab))
 				: DeclarationData.Vehicle.SleeperCabDefault;
 		} }
-		public TankSystem TankSystem { get {
+		public TankSystem? TankSystem { get {
 			return ElementExists(XMLNames.Vehicle_NgTankSystem)
 				? EnumHelper.ParseEnum<TankSystem>(GetElementValue(XMLNames.Vehicle_NgTankSystem))
-				: DeclarationData.Vehicle.TankSystemDefault;
+				: (TankSystem?)null;
 		} }
 
 		public IAdvancedDriverAssistantSystemDeclarationInputData ADAS { get { return this; } }

VectoCore/VectoCore/InputData/FileIO/XML/Engineering/XMLEngineeringVehicleDataProvider.cs

@@ -293,7 +293,7 @@ namespace TUGraz.VectoCore.InputData.FileIO.XML.Engineering
 		public IPTOTransmissionInputData PTOTransmissionInputData { get; private set; }
 		public bool VocationalVehicle { get { return false; } }
 		public bool SleeperCab { get { return true; } }
-		public TankSystem TankSystem { get; }
+		public TankSystem? TankSystem { get; }
 		public IAdvancedDriverAssistantSystemDeclarationInputData ADAS { get { return null; } }
 		public bool ZeroEmissionVehicle { get { return false; } }
 		public bool HybridElectricHDV { get { return false; } }