Fix some sonarcloud issues

Author: StefH

src/System.Linq.Dynamic.Core.NewtonsoftJson/Extensions/JObjectExtensions.cs

@@ -11,7 +11,7 @@ namespace System.Linq.Dynamic.Core.NewtonsoftJson.Extensions;
 /// </summary>
 internal static class JObjectExtensions
 {
-    private class JTokenResolvers : Dictionary<JTokenType, Func<JToken, DynamicJsonClassOptions?, object?>>;
+    private sealed class JTokenResolvers : Dictionary<JTokenType, Func<JToken, DynamicJsonClassOptions?, object?>>;
 
     private static readonly JTokenResolvers Resolvers = new()
     {

src/System.Linq.Dynamic.Core.SystemTextJson/Extensions/JsonDocumentExtensions.cs

@@ -8,7 +8,7 @@ namespace System.Linq.Dynamic.Core.SystemTextJson.Extensions;
 
 internal static class JsonDocumentExtensions
 {
-    private class JTokenResolvers : Dictionary<JsonValueKind, Func<JsonElement, DynamicJsonClassOptions?, object?>>;
+    private sealed class JTokenResolvers : Dictionary<JsonValueKind, Func<JsonElement, DynamicJsonClassOptions?, object?>>;
 
     private static readonly JTokenResolvers Resolvers = new()
     {

src/System.Linq.Dynamic.Core/Extensions/ListExtensions.cs

@@ -5,6 +5,7 @@ namespace System.Linq.Dynamic.Core.Extensions;
 internal static class ListExtensions
 {
     internal static void AddIfNotNull<T>(this IList<T> list, T? value)
+        where T : class
     {
         if (value != null)
         {

src/System.Linq.Dynamic.Core/Parser/ExpressionParser.cs

@@ -1980,7 +1980,7 @@ private bool TryFindPropertyOrField(Type type, string id, Expression? expression
         switch (member)
         {
             case PropertyInfo property:
-                var propertyIsStatic = property?.GetGetMethod().IsStatic ?? property?.GetSetMethod().IsStatic ?? false;
+                var propertyIsStatic = property.GetGetMethod()?.IsStatic ?? property.GetSetMethod()?.IsStatic ?? false;
                 propertyOrFieldExpression = propertyIsStatic ? Expression.Property(null, property) : Expression.Property(expression, property);
                 return true;
 

src/System.Linq.Dynamic.Core/Parser/SupportedMethods/MethodFinder.cs

@@ -10,7 +10,7 @@ internal class MethodFinder
 {
     private readonly ParsingConfig _parsingConfig;
     private readonly IExpressionHelper _expressionHelper;
-    private readonly IDictionary<Type, MethodInfo[]> _cachedMethods;
+    private readonly Dictionary<Type, MethodInfo[]> _cachedMethods;
 
     /// <summary>
     /// #794