Nullable refernce types refactoring

WotBlitzStatisticsPro.GraphQl/MongoSettings.cs

@@ -4,7 +4,7 @@ namespace WotBlitzStatisticsPro.GraphQl
 {
     public class MongoSettings : IMongoSettings
     {
-        public string ConnectionString { get; set; }
-        public string DatabaseName { get; set; }
+        public string ConnectionString { get; set; } = string.Empty;
+        public string DatabaseName { get; set; } = string.Empty;
     }
 }

WotBlitzStatisticsPro.GraphQl/WargamingApiSettings.cs

@@ -4,8 +4,8 @@ namespace WotBlitzStatisticsPro.GraphQl
 {
     /// <inheritdoc />
     public class WargamingApiSettings : IWargamingApiSettings
-	{
+    {
         /// <inheritdoc />
-        public string ApplicationId { get; set; }
-	}
+        public string ApplicationId { get; set; } = string.Empty;
+    }
 }

WotBlitzStatisticsPro.GraphQl/WotBlitzStatisticsPro.GraphQl.csproj

@@ -4,6 +4,7 @@
     <TargetFramework>net5.0</TargetFramework>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <NoWarn>$(NoWarn);1591</NoWarn>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>