diff --git a/samples/client/petstore/csharp/generichost/latest/Tags/src/Org.OpenAPITools/Client/ClientUtils.cs b/samples/client/petstore/csharp/generichost/latest/Tags/src/Org.OpenAPITools/Client/ClientUtils.cs
index f14c41cebb1..a312a586bfa 100644
--- a/samples/client/petstore/csharp/generichost/latest/Tags/src/Org.OpenAPITools/Client/ClientUtils.cs
+++ b/samples/client/petstore/csharp/generichost/latest/Tags/src/Org.OpenAPITools/Client/ClientUtils.cs
@@ -142,6 +142,8 @@ namespace Org.OpenAPITools.Client
                 // https://msdn.microsoft.com/en-us/library/az4se3k1(v=vs.110).aspx#Anchor_8
                 // For example: 2009-06-15T13:45:30.0000000
                 return dateTimeOffset.ToString(format);
+            if (obj is DateOnly dateOnly)
+                return dateOnly.ToString(format);
             if (obj is bool boolean)
                 return boolean
                     ? "true"
diff --git a/samples/client/petstore/csharp/restsharp/net7/EnumMappings/docs/NullableClass.md b/samples/client/petstore/csharp/restsharp/net7/EnumMappings/docs/NullableClass.md
index 67c1052fca9..2d238d6a80c 100644
--- a/samples/client/petstore/csharp/restsharp/net7/EnumMappings/docs/NullableClass.md
+++ b/samples/client/petstore/csharp/restsharp/net7/EnumMappings/docs/NullableClass.md
@@ -8,7 +8,7 @@ Name | Type | Description | Notes
 **NumberProp** | **decimal?** |  | [optional] 
 **BooleanProp** | **bool?** |  | [optional] 
 **StringProp** | **string** |  | [optional] 
-**DateProp** | **DateOnly** |  | [optional] 
+**DateProp** | **DateOnly?** |  | [optional] 
 **DatetimeProp** | **DateTime?** |  | [optional] 
 **ArrayNullableProp** | **List<Object>** |  | [optional] 
 **ArrayAndItemsNullableProp** | **List<Object>** |  | [optional] 
diff --git a/samples/client/petstore/csharp/restsharp/net7/EnumMappings/docs/RequiredClass.md b/samples/client/petstore/csharp/restsharp/net7/EnumMappings/docs/RequiredClass.md
index 685c1c51e03..7f734db8a61 100644
--- a/samples/client/petstore/csharp/restsharp/net7/EnumMappings/docs/RequiredClass.md
+++ b/samples/client/petstore/csharp/restsharp/net7/EnumMappings/docs/RequiredClass.md
@@ -16,9 +16,9 @@ Name | Type | Description | Notes
 **RequiredNotnullableBooleanProp** | **bool** |  | 
 **NotrequiredNullableBooleanProp** | **bool?** |  | [optional] 
 **NotrequiredNotnullableBooleanProp** | **bool** |  | [optional] 
-**RequiredNullableDateProp** | **DateOnly** |  | 
+**RequiredNullableDateProp** | **DateOnly?** |  | 
 **RequiredNotNullableDateProp** | **DateOnly** |  | 
-**NotRequiredNullableDateProp** | **DateOnly** |  | [optional] 
+**NotRequiredNullableDateProp** | **DateOnly?** |  | [optional] 
 **NotRequiredNotnullableDateProp** | **DateOnly** |  | [optional] 
 **RequiredNotnullableDatetimeProp** | **DateTime** |  | 
 **RequiredNullableDatetimeProp** | **DateTime?** |  | 
diff --git a/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Model/FormatTest.cs b/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Model/FormatTest.cs
index be49efc7f71..59c8975b929 100644
--- a/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Model/FormatTest.cs
+++ b/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Model/FormatTest.cs
@@ -71,11 +71,6 @@ namespace Org.OpenAPITools.Model
                 throw new ArgumentNullException("varByte is a required property for FormatTest and cannot be null");
             }
             this.Byte = varByte;
-            // to ensure "date" is required (not null)
-            if (date == null)
-            {
-                throw new ArgumentNullException("date is a required property for FormatTest and cannot be null");
-            }
             this.Date = date;
             // to ensure "password" is required (not null)
             if (password == null)
diff --git a/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Model/NullableClass.cs b/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Model/NullableClass.cs
index 1ae27f1846d..c8fda56e430 100644
--- a/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Model/NullableClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Model/NullableClass.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <param name="objectNullableProp">objectNullableProp.</param>
         /// <param name="objectAndItemsNullableProp">objectAndItemsNullableProp.</param>
         /// <param name="objectItemsNullable">objectItemsNullable.</param>
-        public NullableClass(int? integerProp = default(int?), decimal? numberProp = default(decimal?), bool? booleanProp = default(bool?), string stringProp = default(string), DateOnly dateProp = default(DateOnly), DateTime? datetimeProp = default(DateTime?), List<Object> arrayNullableProp = default(List<Object>), List<Object> arrayAndItemsNullableProp = default(List<Object>), List<Object> arrayItemsNullable = default(List<Object>), Dictionary<string, Object> objectNullableProp = default(Dictionary<string, Object>), Dictionary<string, Object> objectAndItemsNullableProp = default(Dictionary<string, Object>), Dictionary<string, Object> objectItemsNullable = default(Dictionary<string, Object>))
+        public NullableClass(int? integerProp = default(int?), decimal? numberProp = default(decimal?), bool? booleanProp = default(bool?), string stringProp = default(string), DateOnly? dateProp = default(DateOnly?), DateTime? datetimeProp = default(DateTime?), List<Object> arrayNullableProp = default(List<Object>), List<Object> arrayAndItemsNullableProp = default(List<Object>), List<Object> arrayItemsNullable = default(List<Object>), Dictionary<string, Object> objectNullableProp = default(Dictionary<string, Object>), Dictionary<string, Object> objectAndItemsNullableProp = default(Dictionary<string, Object>), Dictionary<string, Object> objectItemsNullable = default(Dictionary<string, Object>))
         {
             this.IntegerProp = integerProp;
             this.NumberProp = numberProp;
@@ -92,7 +92,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets DateProp
         /// </summary>
         [DataMember(Name = "date_prop", EmitDefaultValue = true)]
-        public DateOnly DateProp { get; set; }
+        public DateOnly? DateProp { get; set; }
 
         /// <summary>
         /// Gets or Sets DatetimeProp
diff --git a/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Model/RequiredClass.cs b/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Model/RequiredClass.cs
index 47629c4e52e..76ce29ff67e 100644
--- a/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Model/RequiredClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Model/RequiredClass.cs
@@ -533,7 +533,7 @@ namespace Org.OpenAPITools.Model
         /// <param name="requiredNotnullableArrayOfString">requiredNotnullableArrayOfString (required).</param>
         /// <param name="notrequiredNullableArrayOfString">notrequiredNullableArrayOfString.</param>
         /// <param name="notrequiredNotnullableArrayOfString">notrequiredNotnullableArrayOfString.</param>
-        public RequiredClass(int? requiredNullableIntegerProp = default(int?), int requiredNotnullableintegerProp = default(int), int? notRequiredNullableIntegerProp = default(int?), int notRequiredNotnullableintegerProp = default(int), string requiredNullableStringProp = default(string), string requiredNotnullableStringProp = default(string), string notrequiredNullableStringProp = default(string), string notrequiredNotnullableStringProp = default(string), bool? requiredNullableBooleanProp = default(bool?), bool requiredNotnullableBooleanProp = default(bool), bool? notrequiredNullableBooleanProp = default(bool?), bool notrequiredNotnullableBooleanProp = default(bool), DateOnly requiredNullableDateProp = default(DateOnly), DateOnly requiredNotNullableDateProp = default(DateOnly), DateOnly notRequiredNullableDateProp = default(DateOnly), DateOnly notRequiredNotnullableDateProp = default(DateOnly), DateTime requiredNotnullableDatetimeProp = default(DateTime), DateTime? requiredNullableDatetimeProp = default(DateTime?), DateTime? notrequiredNullableDatetimeProp = default(DateTime?), DateTime notrequiredNotnullableDatetimeProp = default(DateTime), RequiredNullableEnumIntegerEnum requiredNullableEnumInteger = default(RequiredNullableEnumIntegerEnum), RequiredNotnullableEnumIntegerEnum requiredNotnullableEnumInteger = default(RequiredNotnullableEnumIntegerEnum), NotrequiredNullableEnumIntegerEnum? notrequiredNullableEnumInteger = default(NotrequiredNullableEnumIntegerEnum?), NotrequiredNotnullableEnumIntegerEnum? notrequiredNotnullableEnumInteger = default(NotrequiredNotnullableEnumIntegerEnum?), RequiredNullableEnumIntegerOnlyEnum requiredNullableEnumIntegerOnly = default(RequiredNullableEnumIntegerOnlyEnum), RequiredNotnullableEnumIntegerOnlyEnum requiredNotnullableEnumIntegerOnly = default(RequiredNotnullableEnumIntegerOnlyEnum), NotrequiredNullableEnumIntegerOnlyEnum? notrequiredNullableEnumIntegerOnly = default(NotrequiredNullableEnumIntegerOnlyEnum?), NotrequiredNotnullableEnumIntegerOnlyEnum? notrequiredNotnullableEnumIntegerOnly = default(NotrequiredNotnullableEnumIntegerOnlyEnum?), RequiredNotnullableEnumStringEnum requiredNotnullableEnumString = default(RequiredNotnullableEnumStringEnum), RequiredNullableEnumStringEnum requiredNullableEnumString = default(RequiredNullableEnumStringEnum), NotrequiredNullableEnumStringEnum? notrequiredNullableEnumString = default(NotrequiredNullableEnumStringEnum?), NotrequiredNotnullableEnumStringEnum? notrequiredNotnullableEnumString = default(NotrequiredNotnullableEnumStringEnum?), OuterEnumDefaultValue requiredNullableOuterEnumDefaultValue = default(OuterEnumDefaultValue), OuterEnumDefaultValue requiredNotnullableOuterEnumDefaultValue = default(OuterEnumDefaultValue), OuterEnumDefaultValue? notrequiredNullableOuterEnumDefaultValue = default(OuterEnumDefaultValue?), OuterEnumDefaultValue? notrequiredNotnullableOuterEnumDefaultValue = default(OuterEnumDefaultValue?), Guid? requiredNullableUuid = default(Guid?), Guid requiredNotnullableUuid = default(Guid), Guid? notrequiredNullableUuid = default(Guid?), Guid notrequiredNotnullableUuid = default(Guid), List<string> requiredNullableArrayOfString = default(List<string>), List<string> requiredNotnullableArrayOfString = default(List<string>), List<string> notrequiredNullableArrayOfString = default(List<string>), List<string> notrequiredNotnullableArrayOfString = default(List<string>))
+        public RequiredClass(int? requiredNullableIntegerProp = default(int?), int requiredNotnullableintegerProp = default(int), int? notRequiredNullableIntegerProp = default(int?), int notRequiredNotnullableintegerProp = default(int), string requiredNullableStringProp = default(string), string requiredNotnullableStringProp = default(string), string notrequiredNullableStringProp = default(string), string notrequiredNotnullableStringProp = default(string), bool? requiredNullableBooleanProp = default(bool?), bool requiredNotnullableBooleanProp = default(bool), bool? notrequiredNullableBooleanProp = default(bool?), bool notrequiredNotnullableBooleanProp = default(bool), DateOnly? requiredNullableDateProp = default(DateOnly?), DateOnly requiredNotNullableDateProp = default(DateOnly), DateOnly? notRequiredNullableDateProp = default(DateOnly?), DateOnly notRequiredNotnullableDateProp = default(DateOnly), DateTime requiredNotnullableDatetimeProp = default(DateTime), DateTime? requiredNullableDatetimeProp = default(DateTime?), DateTime? notrequiredNullableDatetimeProp = default(DateTime?), DateTime notrequiredNotnullableDatetimeProp = default(DateTime), RequiredNullableEnumIntegerEnum requiredNullableEnumInteger = default(RequiredNullableEnumIntegerEnum), RequiredNotnullableEnumIntegerEnum requiredNotnullableEnumInteger = default(RequiredNotnullableEnumIntegerEnum), NotrequiredNullableEnumIntegerEnum? notrequiredNullableEnumInteger = default(NotrequiredNullableEnumIntegerEnum?), NotrequiredNotnullableEnumIntegerEnum? notrequiredNotnullableEnumInteger = default(NotrequiredNotnullableEnumIntegerEnum?), RequiredNullableEnumIntegerOnlyEnum requiredNullableEnumIntegerOnly = default(RequiredNullableEnumIntegerOnlyEnum), RequiredNotnullableEnumIntegerOnlyEnum requiredNotnullableEnumIntegerOnly = default(RequiredNotnullableEnumIntegerOnlyEnum), NotrequiredNullableEnumIntegerOnlyEnum? notrequiredNullableEnumIntegerOnly = default(NotrequiredNullableEnumIntegerOnlyEnum?), NotrequiredNotnullableEnumIntegerOnlyEnum? notrequiredNotnullableEnumIntegerOnly = default(NotrequiredNotnullableEnumIntegerOnlyEnum?), RequiredNotnullableEnumStringEnum requiredNotnullableEnumString = default(RequiredNotnullableEnumStringEnum), RequiredNullableEnumStringEnum requiredNullableEnumString = default(RequiredNullableEnumStringEnum), NotrequiredNullableEnumStringEnum? notrequiredNullableEnumString = default(NotrequiredNullableEnumStringEnum?), NotrequiredNotnullableEnumStringEnum? notrequiredNotnullableEnumString = default(NotrequiredNotnullableEnumStringEnum?), OuterEnumDefaultValue requiredNullableOuterEnumDefaultValue = default(OuterEnumDefaultValue), OuterEnumDefaultValue requiredNotnullableOuterEnumDefaultValue = default(OuterEnumDefaultValue), OuterEnumDefaultValue? notrequiredNullableOuterEnumDefaultValue = default(OuterEnumDefaultValue?), OuterEnumDefaultValue? notrequiredNotnullableOuterEnumDefaultValue = default(OuterEnumDefaultValue?), Guid? requiredNullableUuid = default(Guid?), Guid requiredNotnullableUuid = default(Guid), Guid? notrequiredNullableUuid = default(Guid?), Guid notrequiredNotnullableUuid = default(Guid), List<string> requiredNullableArrayOfString = default(List<string>), List<string> requiredNotnullableArrayOfString = default(List<string>), List<string> notrequiredNullableArrayOfString = default(List<string>), List<string> notrequiredNotnullableArrayOfString = default(List<string>))
         {
             // to ensure "requiredNullableIntegerProp" is required (not null)
             if (requiredNullableIntegerProp == null)
@@ -567,11 +567,6 @@ namespace Org.OpenAPITools.Model
                 throw new ArgumentNullException("requiredNullableDateProp is a required property for RequiredClass and cannot be null");
             }
             this.RequiredNullableDateProp = requiredNullableDateProp;
-            // to ensure "requiredNotNullableDateProp" is required (not null)
-            if (requiredNotNullableDateProp == null)
-            {
-                throw new ArgumentNullException("requiredNotNullableDateProp is a required property for RequiredClass and cannot be null");
-            }
             this.RequiredNotNullableDateProp = requiredNotNullableDateProp;
             this.RequiredNotnullableDatetimeProp = requiredNotnullableDatetimeProp;
             // to ensure "requiredNullableDatetimeProp" is required (not null)
@@ -708,7 +703,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets RequiredNullableDateProp
         /// </summary>
         [DataMember(Name = "required_nullable_date_prop", IsRequired = true, EmitDefaultValue = true)]
-        public DateOnly RequiredNullableDateProp { get; set; }
+        public DateOnly? RequiredNullableDateProp { get; set; }
 
         /// <summary>
         /// Gets or Sets RequiredNotNullableDateProp
@@ -720,7 +715,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotRequiredNullableDateProp
         /// </summary>
         [DataMember(Name = "not_required_nullable_date_prop", EmitDefaultValue = true)]
-        public DateOnly NotRequiredNullableDateProp { get; set; }
+        public DateOnly? NotRequiredNullableDateProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotRequiredNotnullableDateProp
diff --git a/samples/client/petstore/csharp/restsharp/net7/Petstore/docs/NullableClass.md b/samples/client/petstore/csharp/restsharp/net7/Petstore/docs/NullableClass.md
index 67c1052fca9..2d238d6a80c 100644
--- a/samples/client/petstore/csharp/restsharp/net7/Petstore/docs/NullableClass.md
+++ b/samples/client/petstore/csharp/restsharp/net7/Petstore/docs/NullableClass.md
@@ -8,7 +8,7 @@ Name | Type | Description | Notes
 **NumberProp** | **decimal?** |  | [optional] 
 **BooleanProp** | **bool?** |  | [optional] 
 **StringProp** | **string** |  | [optional] 
-**DateProp** | **DateOnly** |  | [optional] 
+**DateProp** | **DateOnly?** |  | [optional] 
 **DatetimeProp** | **DateTime?** |  | [optional] 
 **ArrayNullableProp** | **List&lt;Object&gt;** |  | [optional] 
 **ArrayAndItemsNullableProp** | **List&lt;Object&gt;** |  | [optional] 
diff --git a/samples/client/petstore/csharp/restsharp/net7/Petstore/docs/RequiredClass.md b/samples/client/petstore/csharp/restsharp/net7/Petstore/docs/RequiredClass.md
index 685c1c51e03..7f734db8a61 100644
--- a/samples/client/petstore/csharp/restsharp/net7/Petstore/docs/RequiredClass.md
+++ b/samples/client/petstore/csharp/restsharp/net7/Petstore/docs/RequiredClass.md
@@ -16,9 +16,9 @@ Name | Type | Description | Notes
 **RequiredNotnullableBooleanProp** | **bool** |  | 
 **NotrequiredNullableBooleanProp** | **bool?** |  | [optional] 
 **NotrequiredNotnullableBooleanProp** | **bool** |  | [optional] 
-**RequiredNullableDateProp** | **DateOnly** |  | 
+**RequiredNullableDateProp** | **DateOnly?** |  | 
 **RequiredNotNullableDateProp** | **DateOnly** |  | 
-**NotRequiredNullableDateProp** | **DateOnly** |  | [optional] 
+**NotRequiredNullableDateProp** | **DateOnly?** |  | [optional] 
 **NotRequiredNotnullableDateProp** | **DateOnly** |  | [optional] 
 **RequiredNotnullableDatetimeProp** | **DateTime** |  | 
 **RequiredNullableDatetimeProp** | **DateTime?** |  | 
diff --git a/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs b/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
index fbdb484b76f..fc3472412e5 100644
--- a/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
+++ b/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
@@ -73,11 +73,6 @@ namespace Org.OpenAPITools.Model
                 throw new ArgumentNullException("varByte is a required property for FormatTest and cannot be null");
             }
             this.Byte = varByte;
-            // to ensure "date" is required (not null)
-            if (date == null)
-            {
-                throw new ArgumentNullException("date is a required property for FormatTest and cannot be null");
-            }
             this.Date = date;
             // to ensure "password" is required (not null)
             if (password == null)
diff --git a/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs b/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs
index 1ae27f1846d..c8fda56e430 100644
--- a/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <param name="objectNullableProp">objectNullableProp.</param>
         /// <param name="objectAndItemsNullableProp">objectAndItemsNullableProp.</param>
         /// <param name="objectItemsNullable">objectItemsNullable.</param>
-        public NullableClass(int? integerProp = default(int?), decimal? numberProp = default(decimal?), bool? booleanProp = default(bool?), string stringProp = default(string), DateOnly dateProp = default(DateOnly), DateTime? datetimeProp = default(DateTime?), List<Object> arrayNullableProp = default(List<Object>), List<Object> arrayAndItemsNullableProp = default(List<Object>), List<Object> arrayItemsNullable = default(List<Object>), Dictionary<string, Object> objectNullableProp = default(Dictionary<string, Object>), Dictionary<string, Object> objectAndItemsNullableProp = default(Dictionary<string, Object>), Dictionary<string, Object> objectItemsNullable = default(Dictionary<string, Object>))
+        public NullableClass(int? integerProp = default(int?), decimal? numberProp = default(decimal?), bool? booleanProp = default(bool?), string stringProp = default(string), DateOnly? dateProp = default(DateOnly?), DateTime? datetimeProp = default(DateTime?), List<Object> arrayNullableProp = default(List<Object>), List<Object> arrayAndItemsNullableProp = default(List<Object>), List<Object> arrayItemsNullable = default(List<Object>), Dictionary<string, Object> objectNullableProp = default(Dictionary<string, Object>), Dictionary<string, Object> objectAndItemsNullableProp = default(Dictionary<string, Object>), Dictionary<string, Object> objectItemsNullable = default(Dictionary<string, Object>))
         {
             this.IntegerProp = integerProp;
             this.NumberProp = numberProp;
@@ -92,7 +92,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets DateProp
         /// </summary>
         [DataMember(Name = "date_prop", EmitDefaultValue = true)]
-        public DateOnly DateProp { get; set; }
+        public DateOnly? DateProp { get; set; }
 
         /// <summary>
         /// Gets or Sets DatetimeProp
diff --git a/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs b/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
index 89a73b791c2..ea386b3a0c5 100644
--- a/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
@@ -530,7 +530,7 @@ namespace Org.OpenAPITools.Model
         /// <param name="requiredNotnullableArrayOfString">requiredNotnullableArrayOfString (required).</param>
         /// <param name="notrequiredNullableArrayOfString">notrequiredNullableArrayOfString.</param>
         /// <param name="notrequiredNotnullableArrayOfString">notrequiredNotnullableArrayOfString.</param>
-        public RequiredClass(int? requiredNullableIntegerProp = default(int?), int requiredNotnullableintegerProp = default(int), int? notRequiredNullableIntegerProp = default(int?), int notRequiredNotnullableintegerProp = default(int), string requiredNullableStringProp = default(string), string requiredNotnullableStringProp = default(string), string notrequiredNullableStringProp = default(string), string notrequiredNotnullableStringProp = default(string), bool? requiredNullableBooleanProp = default(bool?), bool requiredNotnullableBooleanProp = default(bool), bool? notrequiredNullableBooleanProp = default(bool?), bool notrequiredNotnullableBooleanProp = default(bool), DateOnly requiredNullableDateProp = default(DateOnly), DateOnly requiredNotNullableDateProp = default(DateOnly), DateOnly notRequiredNullableDateProp = default(DateOnly), DateOnly notRequiredNotnullableDateProp = default(DateOnly), DateTime requiredNotnullableDatetimeProp = default(DateTime), DateTime? requiredNullableDatetimeProp = default(DateTime?), DateTime? notrequiredNullableDatetimeProp = default(DateTime?), DateTime notrequiredNotnullableDatetimeProp = default(DateTime), RequiredNullableEnumIntegerEnum requiredNullableEnumInteger = default(RequiredNullableEnumIntegerEnum), RequiredNotnullableEnumIntegerEnum requiredNotnullableEnumInteger = default(RequiredNotnullableEnumIntegerEnum), NotrequiredNullableEnumIntegerEnum? notrequiredNullableEnumInteger = default(NotrequiredNullableEnumIntegerEnum?), NotrequiredNotnullableEnumIntegerEnum? notrequiredNotnullableEnumInteger = default(NotrequiredNotnullableEnumIntegerEnum?), RequiredNullableEnumIntegerOnlyEnum requiredNullableEnumIntegerOnly = default(RequiredNullableEnumIntegerOnlyEnum), RequiredNotnullableEnumIntegerOnlyEnum requiredNotnullableEnumIntegerOnly = default(RequiredNotnullableEnumIntegerOnlyEnum), NotrequiredNullableEnumIntegerOnlyEnum? notrequiredNullableEnumIntegerOnly = default(NotrequiredNullableEnumIntegerOnlyEnum?), NotrequiredNotnullableEnumIntegerOnlyEnum? notrequiredNotnullableEnumIntegerOnly = default(NotrequiredNotnullableEnumIntegerOnlyEnum?), RequiredNotnullableEnumStringEnum requiredNotnullableEnumString = default(RequiredNotnullableEnumStringEnum), RequiredNullableEnumStringEnum requiredNullableEnumString = default(RequiredNullableEnumStringEnum), NotrequiredNullableEnumStringEnum? notrequiredNullableEnumString = default(NotrequiredNullableEnumStringEnum?), NotrequiredNotnullableEnumStringEnum? notrequiredNotnullableEnumString = default(NotrequiredNotnullableEnumStringEnum?), OuterEnumDefaultValue requiredNullableOuterEnumDefaultValue = default(OuterEnumDefaultValue), OuterEnumDefaultValue requiredNotnullableOuterEnumDefaultValue = default(OuterEnumDefaultValue), OuterEnumDefaultValue? notrequiredNullableOuterEnumDefaultValue = default(OuterEnumDefaultValue?), OuterEnumDefaultValue? notrequiredNotnullableOuterEnumDefaultValue = default(OuterEnumDefaultValue?), Guid? requiredNullableUuid = default(Guid?), Guid requiredNotnullableUuid = default(Guid), Guid? notrequiredNullableUuid = default(Guid?), Guid notrequiredNotnullableUuid = default(Guid), List<string> requiredNullableArrayOfString = default(List<string>), List<string> requiredNotnullableArrayOfString = default(List<string>), List<string> notrequiredNullableArrayOfString = default(List<string>), List<string> notrequiredNotnullableArrayOfString = default(List<string>))
+        public RequiredClass(int? requiredNullableIntegerProp = default(int?), int requiredNotnullableintegerProp = default(int), int? notRequiredNullableIntegerProp = default(int?), int notRequiredNotnullableintegerProp = default(int), string requiredNullableStringProp = default(string), string requiredNotnullableStringProp = default(string), string notrequiredNullableStringProp = default(string), string notrequiredNotnullableStringProp = default(string), bool? requiredNullableBooleanProp = default(bool?), bool requiredNotnullableBooleanProp = default(bool), bool? notrequiredNullableBooleanProp = default(bool?), bool notrequiredNotnullableBooleanProp = default(bool), DateOnly? requiredNullableDateProp = default(DateOnly?), DateOnly requiredNotNullableDateProp = default(DateOnly), DateOnly? notRequiredNullableDateProp = default(DateOnly?), DateOnly notRequiredNotnullableDateProp = default(DateOnly), DateTime requiredNotnullableDatetimeProp = default(DateTime), DateTime? requiredNullableDatetimeProp = default(DateTime?), DateTime? notrequiredNullableDatetimeProp = default(DateTime?), DateTime notrequiredNotnullableDatetimeProp = default(DateTime), RequiredNullableEnumIntegerEnum requiredNullableEnumInteger = default(RequiredNullableEnumIntegerEnum), RequiredNotnullableEnumIntegerEnum requiredNotnullableEnumInteger = default(RequiredNotnullableEnumIntegerEnum), NotrequiredNullableEnumIntegerEnum? notrequiredNullableEnumInteger = default(NotrequiredNullableEnumIntegerEnum?), NotrequiredNotnullableEnumIntegerEnum? notrequiredNotnullableEnumInteger = default(NotrequiredNotnullableEnumIntegerEnum?), RequiredNullableEnumIntegerOnlyEnum requiredNullableEnumIntegerOnly = default(RequiredNullableEnumIntegerOnlyEnum), RequiredNotnullableEnumIntegerOnlyEnum requiredNotnullableEnumIntegerOnly = default(RequiredNotnullableEnumIntegerOnlyEnum), NotrequiredNullableEnumIntegerOnlyEnum? notrequiredNullableEnumIntegerOnly = default(NotrequiredNullableEnumIntegerOnlyEnum?), NotrequiredNotnullableEnumIntegerOnlyEnum? notrequiredNotnullableEnumIntegerOnly = default(NotrequiredNotnullableEnumIntegerOnlyEnum?), RequiredNotnullableEnumStringEnum requiredNotnullableEnumString = default(RequiredNotnullableEnumStringEnum), RequiredNullableEnumStringEnum requiredNullableEnumString = default(RequiredNullableEnumStringEnum), NotrequiredNullableEnumStringEnum? notrequiredNullableEnumString = default(NotrequiredNullableEnumStringEnum?), NotrequiredNotnullableEnumStringEnum? notrequiredNotnullableEnumString = default(NotrequiredNotnullableEnumStringEnum?), OuterEnumDefaultValue requiredNullableOuterEnumDefaultValue = default(OuterEnumDefaultValue), OuterEnumDefaultValue requiredNotnullableOuterEnumDefaultValue = default(OuterEnumDefaultValue), OuterEnumDefaultValue? notrequiredNullableOuterEnumDefaultValue = default(OuterEnumDefaultValue?), OuterEnumDefaultValue? notrequiredNotnullableOuterEnumDefaultValue = default(OuterEnumDefaultValue?), Guid? requiredNullableUuid = default(Guid?), Guid requiredNotnullableUuid = default(Guid), Guid? notrequiredNullableUuid = default(Guid?), Guid notrequiredNotnullableUuid = default(Guid), List<string> requiredNullableArrayOfString = default(List<string>), List<string> requiredNotnullableArrayOfString = default(List<string>), List<string> notrequiredNullableArrayOfString = default(List<string>), List<string> notrequiredNotnullableArrayOfString = default(List<string>))
         {
             // to ensure "requiredNullableIntegerProp" is required (not null)
             if (requiredNullableIntegerProp == null)
@@ -564,11 +564,6 @@ namespace Org.OpenAPITools.Model
                 throw new ArgumentNullException("requiredNullableDateProp is a required property for RequiredClass and cannot be null");
             }
             this.RequiredNullableDateProp = requiredNullableDateProp;
-            // to ensure "requiredNotNullableDateProp" is required (not null)
-            if (requiredNotNullableDateProp == null)
-            {
-                throw new ArgumentNullException("requiredNotNullableDateProp is a required property for RequiredClass and cannot be null");
-            }
             this.RequiredNotNullableDateProp = requiredNotNullableDateProp;
             this.RequiredNotnullableDatetimeProp = requiredNotnullableDatetimeProp;
             // to ensure "requiredNullableDatetimeProp" is required (not null)
@@ -704,7 +699,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets RequiredNullableDateProp
         /// </summary>
         [DataMember(Name = "required_nullable_date_prop", IsRequired = true, EmitDefaultValue = true)]
-        public DateOnly RequiredNullableDateProp { get; set; }
+        public DateOnly? RequiredNullableDateProp { get; set; }
 
         /// <summary>
         /// Gets or Sets RequiredNotNullableDateProp
@@ -716,7 +711,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotRequiredNullableDateProp
         /// </summary>
         [DataMember(Name = "not_required_nullable_date_prop", EmitDefaultValue = true)]
-        public DateOnly NotRequiredNullableDateProp { get; set; }
+        public DateOnly? NotRequiredNullableDateProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotRequiredNotnullableDateProp