diff --git a/APIMatic.Core.Test/APIMatic.Core.Test.csproj b/APIMatic.Core.Test/APIMatic.Core.Test.csproj
index 6f35c45a..8a7392de 100644
--- a/APIMatic.Core.Test/APIMatic.Core.Test.csproj
+++ b/APIMatic.Core.Test/APIMatic.Core.Test.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFramework>net6.0</TargetFramework>
+        <TargetFramework>net8.0</TargetFramework>
 
         <IsPackable>false</IsPackable>
     </PropertyGroup>
diff --git a/APIMatic.Core.Test/Api/HttpGet/ApiCallGetDynamicError.cs b/APIMatic.Core.Test/Api/HttpGet/ApiCallGetDynamicError.cs
index 67fd9b3e..3cd553cd 100644
--- a/APIMatic.Core.Test/Api/HttpGet/ApiCallGetDynamicError.cs
+++ b/APIMatic.Core.Test/Api/HttpGet/ApiCallGetDynamicError.cs
@@ -14,7 +14,7 @@
 namespace APIMatic.Core.Test.Api.HttpGet
 {
     [TestFixture]
-    internal class ApiCallGetDynamicError : ApiCallTest
+    internal sealed class ApiCallGetDynamicError : ApiCallTest
     {
         [Test]
         public void ApiCall_GetDynamicError_Local_501StausCode()
diff --git a/APIMatic.Core.Test/Api/HttpGet/ApiCallGetTest.cs b/APIMatic.Core.Test/Api/HttpGet/ApiCallGetTest.cs
index ab408a1c..2f7525d4 100644
--- a/APIMatic.Core.Test/Api/HttpGet/ApiCallGetTest.cs
+++ b/APIMatic.Core.Test/Api/HttpGet/ApiCallGetTest.cs
@@ -679,7 +679,7 @@ public void ApiCall_GetNumber_MissingContent()
 
             // Act and Assert
             var exp = Assert.Throws<FormatException>(() => CoreHelper.RunTask(apiCall));
-            Assert.AreEqual("Input string was not in a correct format.", exp.Message);
+            Assert.AreEqual("The input string '' was not in a correct format.", exp.Message);
         }
 
         [Test]
diff --git a/APIMatic.Core.Test/Api/HttpPost/ApiCallPostContainerTest.cs b/APIMatic.Core.Test/Api/HttpPost/ApiCallPostContainerTest.cs
index 21abf68e..46580214 100644
--- a/APIMatic.Core.Test/Api/HttpPost/ApiCallPostContainerTest.cs
+++ b/APIMatic.Core.Test/Api/HttpPost/ApiCallPostContainerTest.cs
@@ -10,7 +10,7 @@
 namespace APIMatic.Core.Test.Api.HttpPost
 {
     [TestFixture]
-    internal class ApiCallPostContainerTest : ApiCallTest
+    internal sealed class ApiCallPostContainerTest : ApiCallTest
     {
         [Test]
         public void ApiCall_PostModelAsContainerData_OKResponse()
diff --git a/APIMatic.Core.Test/Api/HttpPost/ApiCallPostFileTest.cs b/APIMatic.Core.Test/Api/HttpPost/ApiCallPostFileTest.cs
index 7b78bf21..3f48373f 100644
--- a/APIMatic.Core.Test/Api/HttpPost/ApiCallPostFileTest.cs
+++ b/APIMatic.Core.Test/Api/HttpPost/ApiCallPostFileTest.cs
@@ -14,7 +14,7 @@
 namespace APIMatic.Core.Test.Api.HttpPost
 {
     [TestFixture]
-    internal class ApiCallPostFileTest : ApiCallTest
+    internal sealed class ApiCallPostFileTest : ApiCallTest
     {
         [Test]
         public void ApiCall_PostFileData_OKResponse()
diff --git a/APIMatic.Core.Test/Api/HttpPost/ApiCallPostStreamTest.cs b/APIMatic.Core.Test/Api/HttpPost/ApiCallPostStreamTest.cs
index 66df14de..a5605559 100644
--- a/APIMatic.Core.Test/Api/HttpPost/ApiCallPostStreamTest.cs
+++ b/APIMatic.Core.Test/Api/HttpPost/ApiCallPostStreamTest.cs
@@ -11,7 +11,7 @@
 namespace APIMatic.Core.Test.Api.HttpPost
 {
     [TestFixture]
-    internal class ApiCallPostStreamTest : ApiCallTest
+    internal sealed class ApiCallPostStreamTest : ApiCallTest
     {
         [Test]
         public void ApiCall_PostBodyStream_OKResponse()
diff --git a/APIMatic.Core.Test/Api/HttpPost/ApiCallPostTest.cs b/APIMatic.Core.Test/Api/HttpPost/ApiCallPostTest.cs
index f44cd4ee..00715f08 100644
--- a/APIMatic.Core.Test/Api/HttpPost/ApiCallPostTest.cs
+++ b/APIMatic.Core.Test/Api/HttpPost/ApiCallPostTest.cs
@@ -13,7 +13,7 @@
 namespace APIMatic.Core.Test.Api.HttpPost
 {
     [TestFixture]
-    internal class ApiCallPostTest : ApiCallTest
+    internal sealed class ApiCallPostTest : ApiCallTest
     {
         [Test]
         public void ApiCall_PostBody_OKResponse()
diff --git a/APIMatic.Core.Test/Api/HttpPost/ApiCallPostXmlTest.cs b/APIMatic.Core.Test/Api/HttpPost/ApiCallPostXmlTest.cs
index 7b24cc8d..bce27d94 100644
--- a/APIMatic.Core.Test/Api/HttpPost/ApiCallPostXmlTest.cs
+++ b/APIMatic.Core.Test/Api/HttpPost/ApiCallPostXmlTest.cs
@@ -9,7 +9,7 @@
 namespace APIMatic.Core.Test.Api.HttpPost
 {
     [TestFixture]
-    internal class ApiCallPostXmlTest : ApiCallTest
+    internal sealed class ApiCallPostXmlTest : ApiCallTest
     {
         [Test]
         public void ApiCall_PostXmlLong_OKResponse()
diff --git a/APIMatic.Core.Test/AuthenticationTest.cs b/APIMatic.Core.Test/AuthenticationTest.cs
index 4cf147b9..d3c3c923 100644
--- a/APIMatic.Core.Test/AuthenticationTest.cs
+++ b/APIMatic.Core.Test/AuthenticationTest.cs
@@ -139,17 +139,19 @@ public void Multiple_Authentication_AND_Validation_Failure()
                 "-> Missing required header field: TOKEN", exp.Message);
         }
 
-        [Test]
-        public void Multiple_Authentication_AND_All_Missing_Validation_Failure()
-        {
-            var expectedLines = new[]
-            {
-                "Following authentication credentials are required:",
+        private static readonly string[] sourceArray =
+        [
+            "Following authentication credentials are required:",
                 "-> Missing required query field: API-KEY",
                 "-> Missing required query field: TOKEN",
                 "-> Missing required header field: API-KEY",
                 "-> Missing required header field: TOKEN"
-            }.OrderBy(line => line);
+        ];
+
+        [Test]
+        public void Multiple_Authentication_AND_All_Missing_Validation_Failure()
+        {
+            var expectedLines = sourceArray.OrderBy(line => line);
             
             var globalConfiguration = new GlobalConfiguration.Builder()
                 .ServerUrls(new Dictionary<Enum, string>
diff --git a/APIMatic.Core.Test/MockTypes/Models/Containers/ArrayOfMapContainer.cs b/APIMatic.Core.Test/MockTypes/Models/Containers/ArrayOfMapContainer.cs
index 955c4e65..f783369c 100644
--- a/APIMatic.Core.Test/MockTypes/Models/Containers/ArrayOfMapContainer.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/Containers/ArrayOfMapContainer.cs
@@ -28,7 +28,7 @@ public static ArrayOfMapContainer Fromorbit(List<Dictionary<string, Orbit>> valu
         public abstract T Match<T>(Func<List<Dictionary<string, Atom>>, T> atom, Func<List<Dictionary<string, Orbit>>, T> orbit);
 
         [JsonConverter(typeof(UnionTypeCaseConverter<AtomCase, List<Dictionary<string, Atom>>>))]
-        private class AtomCase : ArrayOfMapContainer, ICaseValue<AtomCase, List<Dictionary<string, Atom>>>
+        private sealed class AtomCase : ArrayOfMapContainer, ICaseValue<AtomCase, List<Dictionary<string, Atom>>>
         {
             public List<Dictionary<string, Atom>> value;
 
@@ -54,7 +54,7 @@ public override string ToString()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<OrbitCase, List<Dictionary<string, Orbit>>>))]
-        private class OrbitCase : ArrayOfMapContainer, ICaseValue<OrbitCase, List<Dictionary<string, Orbit>>>
+        private sealed class OrbitCase : ArrayOfMapContainer, ICaseValue<OrbitCase, List<Dictionary<string, Orbit>>>
         {
             public List<Dictionary<string, Orbit>> value;
 
diff --git a/APIMatic.Core.Test/MockTypes/Models/Containers/CustomAnyOfContainer.cs b/APIMatic.Core.Test/MockTypes/Models/Containers/CustomAnyOfContainer.cs
index aa234eb2..09d84325 100644
--- a/APIMatic.Core.Test/MockTypes/Models/Containers/CustomAnyOfContainer.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/Containers/CustomAnyOfContainer.cs
@@ -27,7 +27,7 @@ public static CustomAnyOfContainer FromOrbit(Orbit value)
         public abstract T Match<T>(Func<Atom, T> atom, Func<Orbit, T> orbit);
 
         [JsonConverter(typeof(UnionTypeCaseConverter<AtomCase, Atom>))]
-        private class AtomCase : CustomAnyOfContainer, ICaseValue<AtomCase, Atom>
+        private sealed class AtomCase : CustomAnyOfContainer, ICaseValue<AtomCase, Atom>
         {
             public Atom value;
 
@@ -53,7 +53,7 @@ public override string ToString()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<OrbitCase, Orbit>))]
-        private class OrbitCase : CustomAnyOfContainer, ICaseValue<OrbitCase, Orbit>
+        private sealed class OrbitCase : CustomAnyOfContainer, ICaseValue<OrbitCase, Orbit>
         {
             public Orbit value;
 
diff --git a/APIMatic.Core.Test/MockTypes/Models/Containers/CustomNestedOneOfContainer.cs b/APIMatic.Core.Test/MockTypes/Models/Containers/CustomNestedOneOfContainer.cs
index 72c59eda..183687f1 100644
--- a/APIMatic.Core.Test/MockTypes/Models/Containers/CustomNestedOneOfContainer.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/Containers/CustomNestedOneOfContainer.cs
@@ -27,7 +27,7 @@ public static CustomNestedOneOfContainer Fromorbit(NativeOneOfContainer value)
         public abstract T Match<T>(Func<Atom, T> atom, Func<NativeOneOfContainer, T> nestedOneOf);
 
         [JsonConverter(typeof(UnionTypeCaseConverter<AtomCase, Atom>))]
-        private class AtomCase : CustomNestedOneOfContainer, ICaseValue<AtomCase, Atom>
+        private sealed class AtomCase : CustomNestedOneOfContainer, ICaseValue<AtomCase, Atom>
         {
             public Atom value;
 
@@ -54,7 +54,7 @@ public override string ToString()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<OrbitCase, NativeOneOfContainer>))]
-        private class OrbitCase : CustomNestedOneOfContainer, ICaseValue<OrbitCase, NativeOneOfContainer>
+        private sealed class OrbitCase : CustomNestedOneOfContainer, ICaseValue<OrbitCase, NativeOneOfContainer>
         {
             public NativeOneOfContainer value;
 
diff --git a/APIMatic.Core.Test/MockTypes/Models/Containers/CustomOneOfCollectionContainer.cs b/APIMatic.Core.Test/MockTypes/Models/Containers/CustomOneOfCollectionContainer.cs
index dd1c331c..4998e27c 100644
--- a/APIMatic.Core.Test/MockTypes/Models/Containers/CustomOneOfCollectionContainer.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/Containers/CustomOneOfCollectionContainer.cs
@@ -27,7 +27,7 @@ public static CustomOneOfCollectionContainer Fromorbit(Orbit[] value)
         public abstract T Match<T>(Func<Atom[], T> atom, Func<Orbit[], T> orbit);
 
         [JsonConverter(typeof(UnionTypeCaseConverter<AtomCase, Atom[]>))]
-        private class AtomCase : CustomOneOfCollectionContainer, ICaseValue<AtomCase, Atom[]>
+        private sealed class AtomCase : CustomOneOfCollectionContainer, ICaseValue<AtomCase, Atom[]>
         {
             public Atom[] value;
 
@@ -53,7 +53,7 @@ public override string ToString()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<OrbitCase, Orbit[]>))]
-        private class OrbitCase : CustomOneOfCollectionContainer, ICaseValue<OrbitCase, Orbit[]>
+        private sealed class OrbitCase : CustomOneOfCollectionContainer, ICaseValue<OrbitCase, Orbit[]>
         {
             public Orbit[] value;
 
diff --git a/APIMatic.Core.Test/MockTypes/Models/Containers/CustomOneOfContainer.cs b/APIMatic.Core.Test/MockTypes/Models/Containers/CustomOneOfContainer.cs
index a247ee25..6f2653b4 100644
--- a/APIMatic.Core.Test/MockTypes/Models/Containers/CustomOneOfContainer.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/Containers/CustomOneOfContainer.cs
@@ -27,7 +27,7 @@ public static CustomOneOfContainer Fromorbit(Orbit value)
         public abstract T Match<T>(Func<Atom, T> atom, Func<Orbit, T> orbit);
 
         [JsonConverter(typeof(UnionTypeCaseConverter<AtomCase, Atom>))]
-        private class AtomCase : CustomOneOfContainer, ICaseValue<AtomCase, Atom>
+        private sealed class AtomCase : CustomOneOfContainer, ICaseValue<AtomCase, Atom>
         {
             public Atom value;
 
@@ -54,7 +54,7 @@ public override string ToString()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<OrbitCase, Orbit>))]
-        private class OrbitCase : CustomOneOfContainer, ICaseValue<OrbitCase, Orbit>
+        private sealed class OrbitCase : CustomOneOfContainer, ICaseValue<OrbitCase, Orbit>
         {
             public Orbit value;
 
diff --git a/APIMatic.Core.Test/MockTypes/Models/Containers/CustomOneOfWithDiscContainer.cs b/APIMatic.Core.Test/MockTypes/Models/Containers/CustomOneOfWithDiscContainer.cs
index 96676726..13572347 100644
--- a/APIMatic.Core.Test/MockTypes/Models/Containers/CustomOneOfWithDiscContainer.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/Containers/CustomOneOfWithDiscContainer.cs
@@ -33,7 +33,7 @@ public static CustomOneOfWithDiscContainer FromHelium(Helium value)
         public abstract T Match<T>(Func<Atom, T> atom, Func<Helium, T> helium);
 
         [JsonConverter(typeof(UnionTypeCaseConverter<AtomCase, Atom>))]
-        private class AtomCase : CustomOneOfWithDiscContainer, ICaseValue<AtomCase, Atom>
+        private sealed class AtomCase : CustomOneOfWithDiscContainer, ICaseValue<AtomCase, Atom>
         {
             public Atom value;
 
@@ -60,7 +60,7 @@ public override string ToString()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<HeliumCase, Helium>))]
-        private class HeliumCase : CustomOneOfWithDiscContainer, ICaseValue<HeliumCase, Helium>
+        private sealed class HeliumCase : CustomOneOfWithDiscContainer, ICaseValue<HeliumCase, Helium>
         {
             public Helium value;
 
diff --git a/APIMatic.Core.Test/MockTypes/Models/Containers/EnumAnyOfContainer.cs b/APIMatic.Core.Test/MockTypes/Models/Containers/EnumAnyOfContainer.cs
index 8a178053..3665f619 100644
--- a/APIMatic.Core.Test/MockTypes/Models/Containers/EnumAnyOfContainer.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/Containers/EnumAnyOfContainer.cs
@@ -33,7 +33,7 @@ public static EnumAnyOfContainer FromMonthNumber(MonthNumber value)
         public abstract T Match<T>(Func<WorkingDays, T> workingDays, Func<Days, T> days, Func<MonthNumber, T> monthNumber);
 
         [JsonConverter(typeof(UnionTypeCaseConverter<WorkingDaysCase, WorkingDays>))]
-        private class WorkingDaysCase : EnumAnyOfContainer, ICaseValue<WorkingDaysCase, WorkingDays>
+        private sealed class WorkingDaysCase : EnumAnyOfContainer, ICaseValue<WorkingDaysCase, WorkingDays>
         {
             public WorkingDays value;
 
@@ -60,7 +60,7 @@ public override string ToString()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<DaysCase, Days>))]
-        private class DaysCase : EnumAnyOfContainer, ICaseValue<DaysCase, Days>
+        private sealed class DaysCase : EnumAnyOfContainer, ICaseValue<DaysCase, Days>
         {
             public Days value;
 
@@ -87,7 +87,7 @@ public override string ToString()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<MonthNumberCase, MonthNumber>))]
-        private class MonthNumberCase : EnumAnyOfContainer, ICaseValue<MonthNumberCase, MonthNumber>
+        private sealed class MonthNumberCase : EnumAnyOfContainer, ICaseValue<MonthNumberCase, MonthNumber>
         {
             public MonthNumber value;
 
diff --git a/APIMatic.Core.Test/MockTypes/Models/Containers/MapOfArrayContainer.cs b/APIMatic.Core.Test/MockTypes/Models/Containers/MapOfArrayContainer.cs
index dba04d21..fa98f754 100644
--- a/APIMatic.Core.Test/MockTypes/Models/Containers/MapOfArrayContainer.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/Containers/MapOfArrayContainer.cs
@@ -28,7 +28,7 @@ public static MapOfArrayContainer Fromorbit(Dictionary<string, List<Orbit>> valu
         public abstract T Match<T>(Func<Dictionary<string, List<Atom>>, T> atomDictionay, Func<Dictionary<string, List<Orbit>>, T> orbitsDictionay);
 
         [JsonConverter(typeof(UnionTypeCaseConverter<AtomCase, Dictionary<string, List<Atom>>>))]
-        private class AtomCase : MapOfArrayContainer, ICaseValue<AtomCase, Dictionary<string, List<Atom>>>
+        private sealed class AtomCase : MapOfArrayContainer, ICaseValue<AtomCase, Dictionary<string, List<Atom>>>
         {
             public Dictionary<string, List<Atom>> value;
 
@@ -54,7 +54,7 @@ public override string ToString()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<OrbitCase, Dictionary<string, List<Orbit>>>))]
-        private class OrbitCase : MapOfArrayContainer, ICaseValue<OrbitCase, Dictionary<string, List<Orbit>>>
+        private sealed class OrbitCase : MapOfArrayContainer, ICaseValue<OrbitCase, Dictionary<string, List<Orbit>>>
         {
             public Dictionary<string, List<Orbit>> value;
 
diff --git a/APIMatic.Core.Test/MockTypes/Models/Containers/NativeAnyOfCollectionContainer.cs b/APIMatic.Core.Test/MockTypes/Models/Containers/NativeAnyOfCollectionContainer.cs
index 956cd67c..62e9a55a 100644
--- a/APIMatic.Core.Test/MockTypes/Models/Containers/NativeAnyOfCollectionContainer.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/Containers/NativeAnyOfCollectionContainer.cs
@@ -28,7 +28,7 @@ public static NativeAnyOfCollectionContainer FromMString(string[] value)
         public abstract T Match<T>(Func<double[], T> precisionArray, Func<string[], T> mStringArray);
 
         [JsonConverter(typeof(UnionTypeCaseConverter<PrecisionArrayCase, double[]>), JTokenType.Float)]
-        private class PrecisionArrayCase : NativeAnyOfCollectionContainer, ICaseValue<PrecisionArrayCase, double[]>
+        private sealed class PrecisionArrayCase : NativeAnyOfCollectionContainer, ICaseValue<PrecisionArrayCase, double[]>
         {
             public double[] value;
 
@@ -55,7 +55,7 @@ public override string ToString()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<MStringArrayCase, string[]>), JTokenType.String)]
-        private class MStringArrayCase : NativeAnyOfCollectionContainer, ICaseValue<MStringArrayCase, string[]>
+        private sealed class MStringArrayCase : NativeAnyOfCollectionContainer, ICaseValue<MStringArrayCase, string[]>
         {
             public string[] value;
 
diff --git a/APIMatic.Core.Test/MockTypes/Models/Containers/NativeAnyOfContainer.cs b/APIMatic.Core.Test/MockTypes/Models/Containers/NativeAnyOfContainer.cs
index 9bd4a444..2c82253a 100644
--- a/APIMatic.Core.Test/MockTypes/Models/Containers/NativeAnyOfContainer.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/Containers/NativeAnyOfContainer.cs
@@ -28,7 +28,7 @@ public static NativeAnyOfContainer FromString(string value)
         public abstract T Match<T>(Func<double, T> precision, Func<string, T> mString);
 
         [JsonConverter(typeof(UnionTypeCaseConverter<PrecisionCase, double>), JTokenType.Float)]
-        private class PrecisionCase : NativeAnyOfContainer, ICaseValue<PrecisionCase, double>
+        private sealed class PrecisionCase : NativeAnyOfContainer, ICaseValue<PrecisionCase, double>
         {
             public double value;
 
@@ -54,7 +54,7 @@ public override string ToString()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<StringCase, string>), JTokenType.String)]
-        private class StringCase : NativeAnyOfContainer, ICaseValue<StringCase, string>
+        private sealed class StringCase : NativeAnyOfContainer, ICaseValue<StringCase, string>
         {
             public string value;
 
diff --git a/APIMatic.Core.Test/MockTypes/Models/Containers/NativeDateTimeAnyOfContainer.cs b/APIMatic.Core.Test/MockTypes/Models/Containers/NativeDateTimeAnyOfContainer.cs
index 7175b73d..2020956b 100644
--- a/APIMatic.Core.Test/MockTypes/Models/Containers/NativeDateTimeAnyOfContainer.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/Containers/NativeDateTimeAnyOfContainer.cs
@@ -29,7 +29,7 @@ public static NativeDateTimeAnyOfContainer FromRFC3339DateTime(DateTime value)
         public abstract T Match<T>(Func<DateTime?, T> rfc1123DateTime, Func<DateTime?, T> rfc3339DateTime);
 
         [JsonConverter(typeof(UnionTypeCaseConverter<DateTimeCase, DateTime?>), JTokenType.Date)]
-        private class DateTimeCase : NativeDateTimeAnyOfContainer, ICaseValue<DateTimeCase, DateTime?>, ICustomConverter
+        private sealed class DateTimeCase : NativeDateTimeAnyOfContainer, ICaseValue<DateTimeCase, DateTime?>, ICustomConverter
         {
             public DateTime? value;
 
@@ -61,7 +61,7 @@ public JsonConverter GetJsonConverter()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<DateTimeCase2, DateTime?>), JTokenType.Date)]
-        private class DateTimeCase2 : NativeDateTimeAnyOfContainer, ICaseValue<DateTimeCase2, DateTime?>, ICustomConverter
+        private sealed class DateTimeCase2 : NativeDateTimeAnyOfContainer, ICaseValue<DateTimeCase2, DateTime?>, ICustomConverter
         {
             public DateTime? value;
 
diff --git a/APIMatic.Core.Test/MockTypes/Models/Containers/NativeNullableOneOfContainer.cs b/APIMatic.Core.Test/MockTypes/Models/Containers/NativeNullableOneOfContainer.cs
index 12e680b6..a5473659 100644
--- a/APIMatic.Core.Test/MockTypes/Models/Containers/NativeNullableOneOfContainer.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/Containers/NativeNullableOneOfContainer.cs
@@ -28,7 +28,7 @@ public static NativeNullableOneOfContainer FromMString(string value)
         public abstract T Match<T>(Func<double?, T> precision, Func<string, T> mString);
 
         [JsonConverter(typeof(UnionTypeCaseConverter<PrecisionCase, double?>), JTokenType.Float, JTokenType.Null)]
-        private class PrecisionCase : NativeNullableOneOfContainer, ICaseValue<PrecisionCase, double?>
+        private sealed class PrecisionCase : NativeNullableOneOfContainer, ICaseValue<PrecisionCase, double?>
         {
             public double? value;
 
@@ -54,7 +54,7 @@ public override string ToString()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<MStringCase, string>), JTokenType.String)]
-        private class MStringCase : NativeNullableOneOfContainer, ICaseValue<MStringCase, string>
+        private sealed class MStringCase : NativeNullableOneOfContainer, ICaseValue<MStringCase, string>
         {
             public string value;
 
diff --git a/APIMatic.Core.Test/MockTypes/Models/Containers/NativeOneOfCollectionContainer.cs b/APIMatic.Core.Test/MockTypes/Models/Containers/NativeOneOfCollectionContainer.cs
index fa25256a..ca90c617 100644
--- a/APIMatic.Core.Test/MockTypes/Models/Containers/NativeOneOfCollectionContainer.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/Containers/NativeOneOfCollectionContainer.cs
@@ -35,7 +35,7 @@ public static NativeOneOfCollectionContainer FromCutomTypeDictionary(Dictionary<
         public abstract T Match<T>(Func<double[], T> precision, Func<string[], T> mString, Func<Dictionary<string, Atom>, T> customTypeDictionay);
 
         [JsonConverter(typeof(UnionTypeCaseConverter<PrecisionArrayCase, double[]>), JTokenType.Float)]
-        private class PrecisionArrayCase : NativeOneOfCollectionContainer, ICaseValue<PrecisionArrayCase, double[]>
+        private sealed class PrecisionArrayCase : NativeOneOfCollectionContainer, ICaseValue<PrecisionArrayCase, double[]>
         {
             public double[] value;
 
@@ -62,7 +62,7 @@ public override string ToString()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<MStringArrayCase, string[]>), JTokenType.String)]
-        private class MStringArrayCase : NativeOneOfCollectionContainer, ICaseValue<MStringArrayCase, string[]>
+        private sealed class MStringArrayCase : NativeOneOfCollectionContainer, ICaseValue<MStringArrayCase, string[]>
         {
             public string[] value;
 
@@ -89,7 +89,7 @@ public override string ToString()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<CustomTypeDictionaryCase, Dictionary<string, Atom>>))]
-        private class CustomTypeDictionaryCase : NativeOneOfCollectionContainer, ICaseValue<CustomTypeDictionaryCase, Dictionary<string, Atom>>
+        private sealed class CustomTypeDictionaryCase : NativeOneOfCollectionContainer, ICaseValue<CustomTypeDictionaryCase, Dictionary<string, Atom>>
         {
             public Dictionary<string, Atom> value;
 
diff --git a/APIMatic.Core.Test/MockTypes/Models/Containers/NativeOneOfContainer.cs b/APIMatic.Core.Test/MockTypes/Models/Containers/NativeOneOfContainer.cs
index c9e0b7b0..6fa67444 100644
--- a/APIMatic.Core.Test/MockTypes/Models/Containers/NativeOneOfContainer.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/Containers/NativeOneOfContainer.cs
@@ -28,7 +28,7 @@ public static NativeOneOfContainer FromMString(string value)
         public abstract T Match<T>(Func<double, T> precision, Func<string, T> mString);
 
         [JsonConverter(typeof(UnionTypeCaseConverter<PrecisionCase, double>), JTokenType.Float)]
-        private class PrecisionCase : NativeOneOfContainer, ICaseValue<PrecisionCase, double>
+        private sealed class PrecisionCase : NativeOneOfContainer, ICaseValue<PrecisionCase, double>
         {
             public double value;
 
@@ -55,7 +55,7 @@ public override string ToString()
         }
 
         [JsonConverter(typeof(UnionTypeCaseConverter<MStringCase, string>), JTokenType.String)]
-        private class MStringCase : NativeOneOfContainer, ICaseValue<MStringCase, string>
+        private sealed class MStringCase : NativeOneOfContainer, ICaseValue<MStringCase, string>
         {
             public string value;
 
diff --git a/APIMatic.Core.Test/MockTypes/Models/Containers/TestContainer.cs b/APIMatic.Core.Test/MockTypes/Models/Containers/TestContainer.cs
index 239aa692..a61fa091 100644
--- a/APIMatic.Core.Test/MockTypes/Models/Containers/TestContainer.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/Containers/TestContainer.cs
@@ -26,7 +26,7 @@ public static NativeOneOfContainer FromMString(string value)
 
         public abstract T Match<T>(Func<double, T> precision, Func<string, T> mString);
 
-        private class PrecisionCase : NativeOneOfContainer, ICaseValue<PrecisionCase, double>
+        private sealed class PrecisionCase : NativeOneOfContainer, ICaseValue<PrecisionCase, double>
         {
             public double value;
 
@@ -52,7 +52,7 @@ public override string ToString()
             }
         }
 
-        private class MStringCase : NativeOneOfContainer, ICaseValue<MStringCase, string>
+        private sealed class MStringCase : NativeOneOfContainer, ICaseValue<MStringCase, string>
         {
             public string value;
 
diff --git a/APIMatic.Core.Test/MockTypes/Models/ServerResponse.cs b/APIMatic.Core.Test/MockTypes/Models/ServerResponse.cs
index 3ba0a760..1e9e5855 100644
--- a/APIMatic.Core.Test/MockTypes/Models/ServerResponse.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/ServerResponse.cs
@@ -3,7 +3,7 @@
 
 namespace APIMatic.Core.Test.MockTypes.Models
 {
-    internal class ServerResponse : BaseModel
+    internal sealed class ServerResponse : BaseModel
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="ServerResponse"/> class.
diff --git a/APIMatic.Core.Test/MockTypes/Models/TestModelB.cs b/APIMatic.Core.Test/MockTypes/Models/TestModelB.cs
index ce095c64..25a37bf1 100644
--- a/APIMatic.Core.Test/MockTypes/Models/TestModelB.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/TestModelB.cs
@@ -4,7 +4,7 @@
 
 namespace APIMatic.Core.Test.MockTypes.Models
 {
-    internal class TestModelB
+    internal sealed class TestModelB
     {
         [JsonConverter(typeof(CustomDateTimeConverter), "yyyy'-'MM'-'dd")]
         public DateTime TestDateTime { get; set; }
diff --git a/APIMatic.Core.Test/MockTypes/Models/TestModelC.cs b/APIMatic.Core.Test/MockTypes/Models/TestModelC.cs
index 3b80ae8d..11226d39 100644
--- a/APIMatic.Core.Test/MockTypes/Models/TestModelC.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/TestModelC.cs
@@ -3,7 +3,7 @@
 namespace APIMatic.Core.Test.MockTypes.Models
 {
     [JsogAttribute()]
-    internal class TestModelC
+    internal sealed class TestModelC
     {
         public string Name { get; set; }
     }
diff --git a/APIMatic.Core.Test/MockTypes/Models/TestModelForMapOfDateTime.cs b/APIMatic.Core.Test/MockTypes/Models/TestModelForMapOfDateTime.cs
index 6ea5d652..62368311 100644
--- a/APIMatic.Core.Test/MockTypes/Models/TestModelForMapOfDateTime.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/TestModelForMapOfDateTime.cs
@@ -6,7 +6,7 @@
 
 namespace APIMatic.Core.Test.MockTypes.Models
 {
-    internal class TestModelForMapOfDateTime
+    internal sealed class TestModelForMapOfDateTime
     {
         [JsonConverter(typeof(CoreMapConverter), typeof(IsoDateTimeConverter))]
         public Dictionary<string, DateTime> DateTimePairs { get; set; }
diff --git a/APIMatic.Core.Test/MockTypes/Models/TestModelListOfDateTime.cs b/APIMatic.Core.Test/MockTypes/Models/TestModelListOfDateTime.cs
index e1cfa370..b4267779 100644
--- a/APIMatic.Core.Test/MockTypes/Models/TestModelListOfDateTime.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/TestModelListOfDateTime.cs
@@ -6,7 +6,7 @@
 
 namespace APIMatic.Core.Test.MockTypes.Models
 {
-    internal class TestModelListOfDateTime
+    internal sealed class TestModelListOfDateTime
     {
         [JsonConverter(typeof(CoreListConverter), typeof(IsoDateTimeConverter))]
         public List<DateTime> DateTimes { get; set; }
diff --git a/APIMatic.Core.Test/MockTypes/Models/UnixDateTimeTestModel.cs b/APIMatic.Core.Test/MockTypes/Models/UnixDateTimeTestModel.cs
index be87d1e4..4505b5b6 100644
--- a/APIMatic.Core.Test/MockTypes/Models/UnixDateTimeTestModel.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/UnixDateTimeTestModel.cs
@@ -4,7 +4,7 @@
 
 namespace APIMatic.Core.Test.MockTypes.Models
 {
-    internal class UnixDateTimeTestModel
+    internal sealed class UnixDateTimeTestModel
     {
         [JsonConverter(typeof(UnixDateTimeConverter))]
         [JsonProperty("dateTime")]
diff --git a/APIMatic.Core.Test/MockTypes/Models/UnixDateTimeTestModelFake.cs b/APIMatic.Core.Test/MockTypes/Models/UnixDateTimeTestModelFake.cs
index 79433caf..47e3a6e1 100644
--- a/APIMatic.Core.Test/MockTypes/Models/UnixDateTimeTestModelFake.cs
+++ b/APIMatic.Core.Test/MockTypes/Models/UnixDateTimeTestModelFake.cs
@@ -3,7 +3,7 @@
 
 namespace APIMatic.Core.Test.MockTypes.Models
 {
-    internal class UnixDateTimeTestModelFake
+    internal sealed class UnixDateTimeTestModelFake
     {
         [JsonConverter(typeof(UnixDateTimeConverter))]
         [JsonProperty("dateTime")]
diff --git a/APIMatic.Core.Test/MockTypes/Utilities/CompatibilityFactory.cs b/APIMatic.Core.Test/MockTypes/Utilities/CompatibilityFactory.cs
index 326db113..fab55316 100644
--- a/APIMatic.Core.Test/MockTypes/Utilities/CompatibilityFactory.cs
+++ b/APIMatic.Core.Test/MockTypes/Utilities/CompatibilityFactory.cs
@@ -10,7 +10,7 @@
 
 namespace APIMatic.Core.Test.MockTypes.Utilities
 {
-    internal class CompatibilityFactory : ICompatibilityFactory<HttpRequest, HttpResponse, HttpContext, ApiException>
+    internal sealed class CompatibilityFactory : ICompatibilityFactory<HttpRequest, HttpResponse, HttpContext, ApiException>
     {
         public ApiException CreateApiException(string reason, CoreContext<CoreRequest, CoreResponse> context) =>
             new(reason, CreateHttpContext(context.Request, context.Response));
diff --git a/APIMatic.Core.Test/MockTypes/Utilities/JsonObject.cs b/APIMatic.Core.Test/MockTypes/Utilities/JsonObject.cs
index 1197132f..e856c640 100644
--- a/APIMatic.Core.Test/MockTypes/Utilities/JsonObject.cs
+++ b/APIMatic.Core.Test/MockTypes/Utilities/JsonObject.cs
@@ -35,7 +35,7 @@ internal static JsonObject FromJObject(JObject json)
         }
     }
 
-    internal class JsonObjectSerializer : JsonConverter<JsonObject>
+    internal sealed class JsonObjectSerializer : JsonConverter<JsonObject>
     {
         public override JsonObject ReadJson(JsonReader reader, Type objectType, JsonObject existingValue, bool hasExistingValue, JsonSerializer serializer)
         {
diff --git a/APIMatic.Core.Test/MockTypes/Utilities/JsonValue.cs b/APIMatic.Core.Test/MockTypes/Utilities/JsonValue.cs
index b8ee8e0d..4170bc24 100644
--- a/APIMatic.Core.Test/MockTypes/Utilities/JsonValue.cs
+++ b/APIMatic.Core.Test/MockTypes/Utilities/JsonValue.cs
@@ -76,7 +76,7 @@ public static JsonValue FromArray<T>(List<T> values)
         }
     }
 
-    internal class JsonValueSerializer : JsonConverter<JsonValue>
+    internal sealed class JsonValueSerializer : JsonConverter<JsonValue>
     {
         public override JsonValue ReadJson(JsonReader reader, Type objectType, JsonValue existingValue, bool hasExistingValue, JsonSerializer serializer)
         {
diff --git a/APIMatic.Core.Test/MockTypes/Utilities/TestLogger.cs b/APIMatic.Core.Test/MockTypes/Utilities/TestLogger.cs
index 7294a5cd..78c745d1 100644
--- a/APIMatic.Core.Test/MockTypes/Utilities/TestLogger.cs
+++ b/APIMatic.Core.Test/MockTypes/Utilities/TestLogger.cs
@@ -4,7 +4,7 @@
 
 namespace APIMatic.Core.Test.MockTypes.Utilities
 {
-    internal class TestLogger : ILogger
+    internal sealed class TestLogger : ILogger
     {
         public IList<LogEntry> LoggedMessages { get; } = new List<LogEntry>();
 
@@ -25,7 +25,7 @@ public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Except
             LoggedMessages.Add(new LogEntry(logLevel, message));
         }
 
-        internal class LogEntry
+        internal sealed class LogEntry
         {
             public LogLevel LogLevel { get; }
             public string Message { get; }
diff --git a/APIMatic.Core.Test/TypesTest.cs b/APIMatic.Core.Test/TypesTest.cs
index 5ea4bd51..29cfe91b 100644
--- a/APIMatic.Core.Test/TypesTest.cs
+++ b/APIMatic.Core.Test/TypesTest.cs
@@ -27,7 +27,7 @@ public void MultipartContent_AdditionalHeaders()
             var file = new CoreFileStreamInfo(memStream, "test - stream.file");
             Dictionary<string, IReadOnlyCollection<string>> multipartHeaders = new(StringComparer.OrdinalIgnoreCase)
             {
-                { "myHeader", new[] { "personalHeaderValue" } }
+                { "myHeader", ["personalHeaderValue"] }
             };
             var fileContent = new MultipartFileContent(file, multipartHeaders);
             var content = fileContent.ToHttpContent("file");
diff --git a/APIMatic.Core.Test/Utilities/AnyOfContainerTest.cs b/APIMatic.Core.Test/Utilities/AnyOfContainerTest.cs
index 52097e23..a047ad10 100644
--- a/APIMatic.Core.Test/Utilities/AnyOfContainerTest.cs
+++ b/APIMatic.Core.Test/Utilities/AnyOfContainerTest.cs
@@ -120,14 +120,14 @@ public void TestNativeCollectionType()
             container.Match<VoidType>(
                 precisionArray: value =>
                 {
-                    double[] expectedPrecision = { 0.987 };
+                    double[] expectedPrecision = [0.987];
                     CollectionAssert.AreEqual(expectedPrecision, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
                 },
                 mStringArray: value =>
                 {
-                    string[] expectedStringArray = { "some string array" };
+                    string[] expectedStringArray = ["some string array"];
                     CollectionAssert.AreEqual(expectedStringArray, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
@@ -136,14 +136,14 @@ public void TestNativeCollectionType()
             container.Match<VoidType>(
                  precisionArray: value =>
                  {
-                     double[] expectedPrecision = { 0.987 };
+                     double[] expectedPrecision = [ 0.987 ];
                      CollectionAssert.AreEqual(expectedPrecision, value);
                      Console.WriteLine(string.Join(", ", value));
                      return null;
                  },
                  mStringArray: value =>
                  {
-                     string[] expectedStringArray = { "some string array" };
+                     string[] expectedStringArray = ["some string array"];
                      CollectionAssert.AreEqual(expectedStringArray, value);
                      Console.WriteLine(string.Join(", ", value));
                      return null;
@@ -152,14 +152,14 @@ public void TestNativeCollectionType()
             container.Match<VoidType>(
                  precisionArray: value =>
                  {
-                     double[] expectedPrecision = { 0.987 };
+                     double[] expectedPrecision = [ 0.987 ];
                      CollectionAssert.AreEqual(expectedPrecision, value);
                      Console.WriteLine(string.Join(", ", value));
                      return null;
                  },
                  mStringArray: value =>
                  {
-                     string[] expectedStringArray = { "some string array" };
+                     string[] expectedStringArray = [ "some string array" ];
                      CollectionAssert.AreEqual(expectedStringArray, value);
                      Console.WriteLine(string.Join(", ", value));
                      return null;
@@ -168,14 +168,14 @@ public void TestNativeCollectionType()
             container.Match<VoidType>(
                 precisionArray: value =>
                 {
-                    double[] expectedPrecision = { 0.987 };
+                    double[] expectedPrecision = [ 0.987 ];
                     CollectionAssert.AreEqual(expectedPrecision, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
                 },
                 mStringArray: value =>
                 {
-                    string[] expectedStringArray = { "some string array" };
+                    string[] expectedStringArray = [ "some string array" ];
                     CollectionAssert.AreEqual(expectedStringArray, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
diff --git a/APIMatic.Core.Test/Utilities/Date/CoreListDateTimeConverterTest.cs b/APIMatic.Core.Test/Utilities/Date/CoreListDateTimeConverterTest.cs
index 04c6462c..139a664b 100644
--- a/APIMatic.Core.Test/Utilities/Date/CoreListDateTimeConverterTest.cs
+++ b/APIMatic.Core.Test/Utilities/Date/CoreListDateTimeConverterTest.cs
@@ -9,7 +9,7 @@
 namespace APIMatic.Core.Test.Utilities.Date
 {
     [TestFixture]
-    internal class CoreListDateTimeConverterTest
+    internal sealed class CoreListDateTimeConverterTest
     {
         [Test]
         public void SerializeListOfDateTime()
diff --git a/APIMatic.Core.Test/Utilities/Date/CoreMapDateTimeConverterTest.cs b/APIMatic.Core.Test/Utilities/Date/CoreMapDateTimeConverterTest.cs
index 60484c39..44c4c37d 100644
--- a/APIMatic.Core.Test/Utilities/Date/CoreMapDateTimeConverterTest.cs
+++ b/APIMatic.Core.Test/Utilities/Date/CoreMapDateTimeConverterTest.cs
@@ -9,7 +9,7 @@
 namespace APIMatic.Core.Test.Utilities.Date
 {
     [TestFixture]
-    internal class CoreMapDateTimeConverterTest
+    internal sealed class CoreMapDateTimeConverterTest
     {
         [Test]
         public void SerializeMapOfDateTime()
diff --git a/APIMatic.Core.Test/Utilities/Date/CoreUnixDateTimeConvertorTest.cs b/APIMatic.Core.Test/Utilities/Date/CoreUnixDateTimeConvertorTest.cs
index 66e9bb30..6934b7cd 100644
--- a/APIMatic.Core.Test/Utilities/Date/CoreUnixDateTimeConvertorTest.cs
+++ b/APIMatic.Core.Test/Utilities/Date/CoreUnixDateTimeConvertorTest.cs
@@ -10,7 +10,7 @@
 namespace APIMatic.Core.Test.Utilities.Date
 {
     [TestFixture]
-    internal class CoreUnixDateTimeConvertorTest
+    internal sealed class CoreUnixDateTimeConvertorTest
     {
         [Test]
         public void UnixDateTimeConverter_ReadJson()
diff --git a/APIMatic.Core.Test/Utilities/Date/StringReplacer.cs b/APIMatic.Core.Test/Utilities/Date/StringReplacer.cs
index 01aa33e6..222d75c6 100644
--- a/APIMatic.Core.Test/Utilities/Date/StringReplacer.cs
+++ b/APIMatic.Core.Test/Utilities/Date/StringReplacer.cs
@@ -1,6 +1,6 @@
 namespace APIMatic.Core.Test.Utilities.Date
 {
-    internal class StringReplacer
+    internal sealed class StringReplacer
     {
         internal static string ReplaceBackSlashR(string value)
         {
diff --git a/APIMatic.Core.Test/Utilities/Date/Xml/Rfc1123DateTimeXmlUtilityTest.cs b/APIMatic.Core.Test/Utilities/Date/Xml/Rfc1123DateTimeXmlUtilityTest.cs
index d5cefaf8..96341dd8 100644
--- a/APIMatic.Core.Test/Utilities/Date/Xml/Rfc1123DateTimeXmlUtilityTest.cs
+++ b/APIMatic.Core.Test/Utilities/Date/Xml/Rfc1123DateTimeXmlUtilityTest.cs
@@ -7,7 +7,7 @@
 namespace APIMatic.Core.Test.Utilities.Date.Xml
 {
     [TestFixture]
-    internal class Rfc1123DateTimeXmlUtilityTest
+    internal sealed class Rfc1123DateTimeXmlUtilityTest
     {
         [Test]
         public void StringToRfc1123Date_WithNullString()
diff --git a/APIMatic.Core.Test/Utilities/Date/Xml/Rfc3339DateTimeXmlUtilityTest.cs b/APIMatic.Core.Test/Utilities/Date/Xml/Rfc3339DateTimeXmlUtilityTest.cs
index 8841766e..c6af1419 100644
--- a/APIMatic.Core.Test/Utilities/Date/Xml/Rfc3339DateTimeXmlUtilityTest.cs
+++ b/APIMatic.Core.Test/Utilities/Date/Xml/Rfc3339DateTimeXmlUtilityTest.cs
@@ -7,7 +7,7 @@
 namespace APIMatic.Core.Test.Utilities.Date.Xml
 {
     [TestFixture]
-    internal class Rfc3339DateTimeXmlUtilityTest
+    internal sealed class Rfc3339DateTimeXmlUtilityTest
     {
         [Test]
         public void StringToRfc3339Date_WithEmptyString()
diff --git a/APIMatic.Core.Test/Utilities/Date/Xml/UnixDateTimeXmlConverterTest.cs b/APIMatic.Core.Test/Utilities/Date/Xml/UnixDateTimeXmlConverterTest.cs
index c745d977..159080c8 100644
--- a/APIMatic.Core.Test/Utilities/Date/Xml/UnixDateTimeXmlConverterTest.cs
+++ b/APIMatic.Core.Test/Utilities/Date/Xml/UnixDateTimeXmlConverterTest.cs
@@ -6,7 +6,7 @@
 namespace APIMatic.Core.Test.Utilities.Date.Xml
 {
     [TestFixture]
-    internal class UnixDateTimeXmlConverterTest
+    internal sealed class UnixDateTimeXmlConverterTest
     {
         [Test]
         public void UnixDateToString_WithDate()
diff --git a/APIMatic.Core.Test/Utilities/OneOfContainerTest.cs b/APIMatic.Core.Test/Utilities/OneOfContainerTest.cs
index 991b428b..6fc56f9c 100644
--- a/APIMatic.Core.Test/Utilities/OneOfContainerTest.cs
+++ b/APIMatic.Core.Test/Utilities/OneOfContainerTest.cs
@@ -159,14 +159,14 @@ public void TestNativeCollectionType()
             container.Match<VoidType>(
                 precision: value =>
                 {
-                    double[] expectedPrecision = { 0.987, 0.6987 };
+                    double[] expectedPrecision = [ 0.987, 0.6987 ];
                     CollectionAssert.AreEqual(expectedPrecision, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
                 },
                 mString: value =>
                 {
-                    string[] expectedStringArray = { "some string array", "test" };
+                    string[] expectedStringArray = [ "some string array", "test" ];
                     CollectionAssert.AreEqual(expectedStringArray, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
@@ -185,14 +185,14 @@ public void TestNativeCollectionType()
             container.Match<VoidType>(
                 precision: value =>
                 {
-                    double[] expectedPrecision = { 0.987, 0.6987 };
+                    double[] expectedPrecision = [ 0.987, 0.6987 ];
                     CollectionAssert.AreEqual(expectedPrecision, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
                 },
                 mString: value =>
                 {
-                    string[] expectedStringArray = { "some string array", "test" };
+                    string[] expectedStringArray = [ "some string array", "test" ];
                     CollectionAssert.AreEqual(expectedStringArray, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
@@ -211,14 +211,14 @@ public void TestNativeCollectionType()
             container.Match<VoidType>(
                 precision: value =>
                 {
-                    double[] expectedPrecision = { 0.987, 0.6987 };
+                    double[] expectedPrecision = [0.987, 0.6987];
                     CollectionAssert.AreEqual(expectedPrecision, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
                 },
                 mString: value =>
                 {
-                    string[] expectedStringArray = { "some string array", "test" };
+                    string[] expectedStringArray = ["some string array", "test"];
                     CollectionAssert.AreEqual(expectedStringArray, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
@@ -237,14 +237,14 @@ public void TestNativeCollectionType()
             container.Match<VoidType>(
                 precision: value =>
                 {
-                    double[] expectedPrecision = { 0.987, 0.6987 };
+                    double[] expectedPrecision = [0.987, 0.6987];
                     CollectionAssert.AreEqual(expectedPrecision, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
                 },
                 mString: value =>
                 {
-                    string[] expectedStringArray = { "some string array", "test" };
+                    string[] expectedStringArray = ["some string array", "test"];
                     CollectionAssert.AreEqual(expectedStringArray, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
@@ -264,14 +264,14 @@ public void TestNativeCollectionType()
             container.Match<VoidType>(
                 precision: value =>
                 {
-                    double[] expectedPrecision = { 0.987, 0.6987 };
+                    double[] expectedPrecision = [0.987, 0.6987];
                     CollectionAssert.AreEqual(expectedPrecision, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
                 },
                 mString: value =>
                 {
-                    string[] expectedStringArray = { "some string array", "test" };
+                    string[] expectedStringArray = ["some string array", "test"];
                     CollectionAssert.AreEqual(expectedStringArray, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
@@ -290,14 +290,14 @@ public void TestNativeCollectionType()
             container.Match<VoidType>(
                 precision: value =>
                 {
-                    double[] expectedPrecision = { 0.987, 0.6987 };
+                    double[] expectedPrecision = [0.987, 0.6987];
                     CollectionAssert.AreEqual(expectedPrecision, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
                 },
                 mString: value =>
                 {
-                    string[] expectedStringArray = { "some string array", "test" };
+                    string[] expectedStringArray = ["some string array", "test"];
                     CollectionAssert.AreEqual(expectedStringArray, value);
                     Console.WriteLine(string.Join(", ", value));
                     return null;
@@ -572,7 +572,7 @@ public void TestCustomTypeCollection()
                 atom: value =>
                 {
                     Atom expectedAtom = new Atom(12, 13);
-                    Atom[] expected = { expectedAtom };
+                    Atom[] expected = [expectedAtom];
                     Assert.AreEqual(expected, value);
                     Console.WriteLine(value);
                     return null;
@@ -580,7 +580,7 @@ public void TestCustomTypeCollection()
                 orbit: value =>
                 {
                     Orbit expectedOrbit = new Orbit(12, "3");
-                    Orbit[] expected = { expectedOrbit };
+                    Orbit[] expected = [expectedOrbit];
                     Assert.AreEqual(expected, value);
                     Console.WriteLine(value);
                     return null;
@@ -590,7 +590,7 @@ public void TestCustomTypeCollection()
                 atom: value =>
                 {
                     Atom expectedAtom = new Atom(12, 13);
-                    Atom[] expected = { expectedAtom };
+                    Atom[] expected = [expectedAtom];
                     Assert.AreEqual(expected, value);
                     Console.WriteLine(value);
                     return null;
@@ -598,7 +598,7 @@ public void TestCustomTypeCollection()
                 orbit: value =>
                 {
                     Orbit expectedOrbit = new Orbit(12, "3");
-                    Orbit[] expected = { expectedOrbit };
+                    Orbit[] expected = [expectedOrbit];
                     Assert.AreEqual(expected, value);
                     Console.WriteLine(value);
                     return null;
@@ -608,7 +608,7 @@ public void TestCustomTypeCollection()
                 atom: value =>
                 {
                     Atom expectedAtom = new Atom(12, 13);
-                    Atom[] expected = { expectedAtom };
+                    Atom[] expected = [expectedAtom];
                     Assert.AreEqual(expected, value);
                     Console.WriteLine(value);
                     return null;
@@ -616,7 +616,7 @@ public void TestCustomTypeCollection()
                 orbit: value =>
                 {
                     Orbit expectedOrbit = new Orbit(12, "3");
-                    Orbit[] expected = { expectedOrbit };
+                    Orbit[] expected = [expectedOrbit];
                     Assert.AreEqual(expected, value);
                     Console.WriteLine(value);
                     return null;
@@ -626,7 +626,7 @@ public void TestCustomTypeCollection()
                 atom: value =>
                 {
                     Atom expectedAtom = new Atom(12, 13);
-                    Atom[] expected = { expectedAtom };
+                    Atom[] expected = [expectedAtom];
                     Assert.AreEqual(expected, value);
                     Console.WriteLine(value);
                     return null;
@@ -634,7 +634,7 @@ public void TestCustomTypeCollection()
                 orbit: value =>
                 {
                     Orbit expectedOrbit = new Orbit(12, "3");
-                    Orbit[] expected = { expectedOrbit };
+                    Orbit[] expected = [expectedOrbit];
                     Assert.AreEqual(expected, value);
                     Console.WriteLine(value);
                     return null;
diff --git a/APIMatic.Core.Test/Utilities/TestHelperTest.cs b/APIMatic.Core.Test/Utilities/TestHelperTest.cs
index 8fcd3cc1..19b90c31 100644
--- a/APIMatic.Core.Test/Utilities/TestHelperTest.cs
+++ b/APIMatic.Core.Test/Utilities/TestHelperTest.cs
@@ -7,7 +7,7 @@
 namespace APIMatic.Core.Test.Utilities
 {
     [TestFixture]
-    internal class TestHelperTest
+    internal sealed class TestHelperTest
     {
         private const string OBJECT_STRING = "[{\"name\":\"Shahid Khaliq\",\"age\":5147483645,\"address\":\"H # 531, S # 20\",\"uid\":\"123321\",\"birthday\":\"1994-02-13\",\"birthtime\":\"1994-02-13T14:01:54.9571247Z\",\"salary\":20000,\"department\":\"Software Development\",\"joiningDay\":\"Saturday\",\"workingDays\":[\"Monday\",\"Tuesday\",\"Friday\"],\"boss\":{\"personType\":\"Boss\",\"name\":\"Zeeshan Ejaz\",\"age\":5147483645,\"address\":\"H # 531, S # 20\",\"uid\":\"123321\",\"birthday\":\"1994-02-13\",\"birthtime\":\"1994-02-13T14:01:54.9571247Z\",\"salary\":20000,\"department\":\"Software Development\",\"joiningDay\":\"Saturday\",\"workingDays\":[\"Monday\",\"Tuesday\",\"Friday\"],\"dependents\":[{\"name\":\"Future Wife\",\"age\":5147483649,\"address\":\"H # 531, S # 20\",\"uid\":\"123412\",\"birthday\":\"1994-02-13\",\"birthtime\":\"1994-02-13T14:01:54.9571247Z\"},{\"name\":\"Future Kid\",\"age\":5147483648,\"address\":\"H # 531, S # 20\",\"uid\":\"312341\",\"birthday\":\"1994-02-13\",\"birthtime\":\"1994-02-13T14:01:54.9571247Z\"}],\"hiredAt\":\"Sun, 06 Nov 1994 08:49:37 GMT\",\"promotedAt\":1484719381},\"dependents\":[{\"name\":\"Future Wife\",\"age\":5147483649,\"address\":\"H # 531, S # 20\",\"uid\":\"123412\",\"birthday\":\"1994-02-13\",\"birthtime\":\"1994-02-13T14:01:54.9571247Z\"},{\"name\":\"Future Kid\",\"age\":5147483648,\"address\":\"H # 531, S # 20\",\"uid\":\"312341\",\"birthday\":\"1994-02-13\",\"birthtime\":\"1994-02-13T14:01:54.9571247Z\"}],\"hiredAt\":\"Sun, 06 Nov 1994 08:49:37 GMT\"},{\"name\":\"Shahid Khaliq\",\"age\":5147483645,\"address\":\"H # 531, S # 20\",\"uid\":\"123321\",\"birthday\":\"1994-02-13\",\"birthtime\":\"1994-02-13T14:01:54.9571247Z\",\"salary\":20000,\"department\":\"Software Development\",\"joiningDay\":\"Saturday\",\"workingDays\":[\"Monday\",\"Tuesday\",\"Friday\"],\"boss\":{\"personType\":\"Boss\",\"name\":\"Zeeshan Ejaz\",\"age\":5147483645,\"address\":\"H # 531, S # 20\",\"uid\":\"123321\",\"birthday\":\"1994-02-13\",\"birthtime\":\"1994-02-13T14:01:54.9571247Z\",\"salary\":20000,\"department\":\"Software Development\",\"joiningDay\":\"Saturday\",\"workingDays\":[\"Monday\",\"Tuesday\",\"Friday\"],\"dependents\":[{\"name\":\"Future Wife\",\"age\":5147483649,\"address\":\"H # 531, S # 20\",\"uid\":\"123412\",\"birthday\":\"1994-02-13\",\"birthtime\":\"1994-02-13T14:01:54.9571247Z\"},{\"name\":\"Future Kid\",\"age\":5147483648,\"address\":\"H # 531, S # 20\",\"uid\":\"312341\",\"birthday\":\"1994-02-13\",\"birthtime\":\"1994-02-13T14:01:54.9571247Z\"}],\"hiredAt\":\"Sun, 06 Nov 1994 08:49:37 GMT\",\"promotedAt\":1484719381},\"dependents\":[{\"name\":\"Future Wife\",\"age\":5147483649,\"address\":\"H # 531, S # 20\",\"uid\":\"123412\",\"birthday\":\"1994-02-13\",\"birthtime\":\"1994-02-13T14:01:54.9571247Z\"},{\"name\":\"Future Kid\",\"age\":5147483648,\"address\":\"H # 531, S # 20\",\"uid\":\"312341\",\"birthday\":\"1994-02-13\",\"birthtime\":\"1994-02-13T14:01:54.9571247Z\"}],\"hiredAt\":\"Sun, 06 Nov 1994 08:49:37 GMT\"}]";
 
diff --git a/APIMatic.Core.Test/Utilities/XmlUtilityTest.cs b/APIMatic.Core.Test/Utilities/XmlUtilityTest.cs
index d3fe72d1..ee1c69ee 100644
--- a/APIMatic.Core.Test/Utilities/XmlUtilityTest.cs
+++ b/APIMatic.Core.Test/Utilities/XmlUtilityTest.cs
@@ -7,7 +7,7 @@
 namespace APIMatic.Core.Test.Utilities
 {
     [TestFixture]
-    internal class XmlUtilityTest
+    internal sealed class XmlUtilityTest
     {
         [Test]
         public void ToXml_NullObject()
@@ -21,13 +21,10 @@ public void ToXml_NullObject()
         [Test]
         public void ModelsArrayToXml_WithoutArrayName()
         {
-            List<TestModel> testModels = new List<TestModel>()
-            {
-                new TestModel()
-                {
-                    Integers = new int[] { 1, 2, 3 }
-                }
-            };
+            List<TestModel> testModels =
+            [
+                new TestModel() { Integers = [1, 2, 3] }
+            ];
 
             string expected = "<ArrayOfTestModel xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\">\n  <TestModel>\n    <TestDateTime>0001-01-01T00:00:00</TestDateTime>\n    <Integers>\n      <int>1</int>\n      <int>2</int>\n      <int>3</int>\n    </Integers>\n  </TestModel>\n</ArrayOfTestModel>";
             string actual = StringReplacer.ReplaceBackSlashR(XmlUtility.ModelsArrayToXml(testModels));
@@ -37,13 +34,10 @@ public void ModelsArrayToXml_WithoutArrayName()
         [Test]
         public void ModelsArrayToXml_WithArrayItemName()
         {
-            List<TestModel> testModels = new List<TestModel>()
-            {
-                new TestModel()
-                {
-                    Integers = new int[] { 1, 2, 3 }
-                }
-            };
+            List<TestModel> testModels =
+            [
+                new TestModel() { Integers = [1, 2, 3] }
+            ];
 
             string expected = "<TestModel xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\">\n  <TestDateTime>0001-01-01T00:00:00</TestDateTime>\n  <Integers>\n    <int>1</int>\n    <int>2</int>\n    <int>3</int>\n  </Integers>\n</TestModel>";
             string actual = StringReplacer.ReplaceBackSlashR(XmlUtility.ModelsArrayToXml(testModels, arrayItemName: "TestModel"));
@@ -62,13 +56,10 @@ public void ModelsArrayToXml_NullList()
         [Test]
         public void ModelsArrayToXml_WithArrayName()
         {
-            List<TestModel> testModels = new List<TestModel>()
-            {
-                new TestModel()
-                {
-                    Integers = new int[] { 1, 2, 3 }
-                }
-            };
+            List<TestModel> testModels =
+            [
+                new TestModel() { Integers = [1, 2, 3] }
+            ];
 
             string expected = "<abd>\n  <xyz xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\">\n    <TestDateTime>0001-01-01T00:00:00</TestDateTime>\n    <Integers>\n      <int>1</int>\n      <int>2</int>\n      <int>3</int>\n    </Integers>\n  </xyz>\n</abd>";
             string actual = StringReplacer.ReplaceBackSlashR(XmlUtility.ModelsArrayToXml(testModels, arrayName: "abd", arrayItemName: "xyz"));
@@ -78,10 +69,7 @@ public void ModelsArrayToXml_WithArrayName()
         [Test]
         public void NativeTypesArrayFromXml_WithArrayName()
         {
-            List<string> expected = new List<string>()
-            {
-                "alpha", "beta", "gamma"
-            };
+            List<string> expected = ["alpha", "beta", "gamma"];
 
             string nativeObjectString = "<root>\r\n  <String>alpha</String>\r\n  <String>beta</String>\r\n  <String>gamma</String>\r\n</root>";
             List<string> actual = XmlUtility.NativeTypesArrayFromXml<string>(nativeObjectString);
@@ -99,10 +87,7 @@ public void NativeTypesArrayFromXml_NullString()
         [Test]
         public void NativeTypesArrayToXml_WithArrayName()
         {
-            List<string> testModels = new List<string>()
-            {
-                "alpha", "beta", "gamma"
-            };
+            List<string> testModels = ["alpha", "beta", "gamma"];
 
             string expected = "<root>\n  <String>alpha</String>\n  <String>beta</String>\n  <String>gamma</String>\n</root>";
             string actual = XmlUtility.NativeTypesArrayToXml(testModels, arrayName: "root");
@@ -112,10 +97,7 @@ public void NativeTypesArrayToXml_WithArrayName()
         [Test]
         public void NativeTypesArrayToXml_WithoutArrayName()
         {
-            List<string> testModels = new List<string>()
-            {
-                "alpha", "beta", "gamma"
-            };
+            List<string> testModels = ["alpha", "beta", "gamma"];
 
             string expected = "<String>\n  <String>alpha</String>\n  <String>beta</String>\n  <String>gamma</String>\n</String>";
             string actual = StringReplacer.ReplaceBackSlashR(XmlUtility.NativeTypesArrayToXml(testModels));
@@ -142,10 +124,7 @@ public void FromXml_EmptyString()
         [Test]
         public void FromXml_ValidInput()
         {
-            List<string> expected = new List<string>()
-            {
-                "alpha", "beta", "gamma"
-            };
+            List<string> expected = ["alpha", "beta", "gamma"];
 
             string local = XmlUtility.ToXml(expected, rootName: "root");
             var actual = XmlUtility.FromXml<List<string>>(local, rootName: "root");