fix nullable

Unosquare.RaspberryIO/Camera/CameraColor.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Linq;
-
 using Swan;
 
 namespace Unosquare.RaspberryIO.Camera {

Unosquare.RaspberryIO/Camera/CameraController.cs

@@ -1,7 +1,9 @@
+#nullable enable
+
 using System;
 using System.IO;
 using System.Threading;
-using System.Threading.Tasks;
+using System.Threading.Tasks;
 
 using Swan;
 

Unosquare.RaspberryIO/Camera/CameraRect.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Globalization;
 
-using Swan;
+using Swan;
 
 namespace Unosquare.RaspberryIO.Camera {
   /// <summary>

Unosquare.RaspberryIO/Camera/CameraSettingsBase.cs

@@ -1,3 +1,5 @@
+#nullable enable
+
 using System;
 using System.Globalization;
 using System.Text;
@@ -298,8 +300,7 @@ namespace Unosquare.RaspberryIO.Camera {
       }
 
       if(this.ImageColorEffectU >= 0 && this.ImageColorEffectV >= 0) {
-        _ = sb.Append(
-            $" -cfx {this.ImageColorEffectU.Clamp(0, 255).ToString(Ci)}:{this.ImageColorEffectV.Clamp(0, 255).ToString(Ci)}");
+        _ = sb.Append($" -cfx {this.ImageColorEffectU.Clamp(0, 255).ToString(Ci)}:{this.ImageColorEffectV.Clamp(0, 255).ToString(Ci)}");
       }
 
       if(this.CaptureMeteringMode != CameraMeteringMode.Average) {
@@ -330,8 +331,7 @@ namespace Unosquare.RaspberryIO.Camera {
         _ = sb.Append($" -drc {this.CaptureDynamicRangeCompensation.ToString().ToLowerInvariant()}");
       }
 
-      if(this.CaptureWhiteBalanceControl == CameraWhiteBalanceMode.Off &&
-          (this.CaptureWhiteBalanceGainBlue != 0M || this.CaptureWhiteBalanceGainRed != 0M)) {
+      if(this.CaptureWhiteBalanceControl == CameraWhiteBalanceMode.Off && (this.CaptureWhiteBalanceGainBlue != 0M || this.CaptureWhiteBalanceGainRed != 0M)) {
         _ = sb.Append($" -awbg {this.CaptureWhiteBalanceGainBlue.ToString(Ci)},{this.CaptureWhiteBalanceGainRed.ToString(Ci)}");
       }
 

Unosquare.RaspberryIO/Camera/CameraVideoSettings.cs

@@ -63,7 +63,7 @@ namespace Unosquare.RaspberryIO.Camera {
     /// <summary>
     /// Specifies the path to save video files.
     /// </summary>
-    public String? VideoFileName {
+    public String VideoFileName {
       get; set;
     }
 

Unosquare.RaspberryIO/Camera/Enums.cs

@@ -1,6 +1,6 @@
-namespace Unosquare.RaspberryIO.Camera {
-  using System;
+using System;
 
+namespace Unosquare.RaspberryIO.Camera {
   /// <summary>
   /// Defines the available encoding formats for the Raspberry Pi camera module.
   /// </summary>