diff --git a/bin/configs/csharp-httpclient-net9.yaml b/bin/configs/csharp-httpclient-net9.yaml
index b1ce09e64d1..a3198514cdb 100644
--- a/bin/configs/csharp-httpclient-net9.yaml
+++ b/bin/configs/csharp-httpclient-net9.yaml
@@ -11,3 +11,4 @@ additionalProperties:
   useOneOfDiscriminatorLookup: true
   targetFramework: net9.0
   equatable: true
+  nullableReferenceTypes: true
diff --git a/bin/configs/csharp-restsharp-net8-compareNetObjects.yaml b/bin/configs/csharp-restsharp-net8-compareNetObjects.yaml
index 89ee23c7e9f..06c46301cf8 100644
--- a/bin/configs/csharp-restsharp-net8-compareNetObjects.yaml
+++ b/bin/configs/csharp-restsharp-net8-compareNetObjects.yaml
@@ -8,3 +8,4 @@ additionalProperties:
   targetFramework: net8.0
   useCompareNetObjects: "true"
   equatable: true
+  nullableReferenceTypes: true
diff --git a/bin/configs/csharp-unityWebRequest-net9.yaml b/bin/configs/csharp-unityWebRequest-net9.yaml
index b5e84fae852..3d013694f41 100644
--- a/bin/configs/csharp-unityWebRequest-net9.yaml
+++ b/bin/configs/csharp-unityWebRequest-net9.yaml
@@ -7,3 +7,4 @@ library: unityWebRequest
 additionalProperties:
   targetFramework: net9.0
   equatable: true
+  nullableReferenceTypes: true
\ No newline at end of file
diff --git a/modules/openapi-generator/src/main/resources/csharp/modelGeneric.mustache b/modules/openapi-generator/src/main/resources/csharp/modelGeneric.mustache
index b5a75b6d46c..c5de34fe24f 100644
--- a/modules/openapi-generator/src/main/resources/csharp/modelGeneric.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp/modelGeneric.mustache
@@ -47,11 +47,11 @@
         */
         {{/example}}
         {{^conditionalSerialization}}
-        [DataMember(Name = "{{baseName}}"{{#required}}, IsRequired = true{{/required}}, EmitDefaultValue = {{#vendorExtensions.x-emit-default-value}}true{{/vendorExtensions.x-emit-default-value}}{{^vendorExtensions.x-emit-default-value}}{{#required}}true{{/required}}{{^required}}{{#isBoolean}}true{{/isBoolean}}{{^isBoolean}}{{#isNullable}}true{{/isNullable}}{{^isNullable}}false{{/isNullable}}{{/isBoolean}}{{/required}}{{/vendorExtensions.x-emit-default-value}})]
+        [DataMember(Name = "{{baseName}}"{{#required}}, IsRequired = true{{/required}}, EmitDefaultValue = {{#isNullable}}true{{/isNullable}}{{^isNullable}}{{#vendorExtensions.x-is-value-type}}true{{/vendorExtensions.x-is-value-type}}{{^vendorExtensions.x-is-value-type}}false{{/vendorExtensions.x-is-value-type}}{{/isNullable}})]
         {{#deprecated}}
         [Obsolete]
         {{/deprecated}}
-        public {{{complexType}}}{{^complexType}}{{{datatypeWithEnum}}}{{/complexType}}{{^isContainer}}{{^required}}?{{/required}}{{/isContainer}} {{name}} { get; set; }
+        public {{{complexType}}}{{^complexType}}{{{datatypeWithEnum}}}{{/complexType}}{{#nullableReferenceTypes}}{{^isContainer}}{{^required}}{{#isNullable}}?{{/isNullable}}{{/required}}{{/isContainer}}{{#isContainer}}{{#isNullable}}{{^required}}?{{/required}}{{/isNullable}}{{/isContainer}}{{/nullableReferenceTypes}} {{name}} { get; set; }
         {{#isReadOnly}}
 
         /// <summary>
@@ -66,11 +66,11 @@
         {{/conditionalSerialization}}
         {{#conditionalSerialization}}
         {{#isReadOnly}}
-        [DataMember(Name = "{{baseName}}"{{#required}}, IsRequired = true{{/required}}, EmitDefaultValue = {{#vendorExtensions.x-emit-default-value}}true{{/vendorExtensions.x-emit-default-value}}{{^vendorExtensions.x-emit-default-value}}{{#required}}true{{/required}}{{^required}}{{#isBoolean}}true{{/isBoolean}}{{^isBoolean}}{{#isNullable}}true{{/isNullable}}{{^isNullable}}false{{/isNullable}}{{/isBoolean}}{{/required}}{{/vendorExtensions.x-emit-default-value}})]
+        [DataMember(Name = "{{baseName}}"{{#required}}, IsRequired = true{{/required}}, EmitDefaultValue = {{#isNullable}}true{{/isNullable}}{{^isNullable}}{{#vendorExtensions.x-is-value-type}}true{{/vendorExtensions.x-is-value-type}}{{^vendorExtensions.x-is-value-type}}false{{/vendorExtensions.x-is-value-type}}{{/isNullable}})]
         {{#deprecated}}
         [Obsolete]
         {{/deprecated}}
-        public {{{complexType}}}{{^complexType}}{{{datatypeWithEnum}}}{{/complexType}}{{^isContainer}}{{^required}}?{{/required}}{{/isContainer}} {{name}} { get; set; }
+        public {{{complexType}}}{{^complexType}}{{{datatypeWithEnum}}}{{/complexType}}{{#nullableReferenceTypes}}{{^isContainer}}{{^required}}{{#isNullable}}?{{/isNullable}}{{/required}}{{/isContainer}}{{#isContainer}}{{#isNullable}}{{^required}}?{{/required}}{{/isNullable}}{{/isContainer}}{{/nullableReferenceTypes}} {{name}} { get; set; }
 
 
         /// <summary>
@@ -84,11 +84,11 @@
         {{/isReadOnly}}
 
         {{^isReadOnly}}
-        [DataMember(Name = "{{baseName}}"{{#required}}, IsRequired = true{{/required}}, EmitDefaultValue = {{#vendorExtensions.x-emit-default-value}}true{{/vendorExtensions.x-emit-default-value}}{{^vendorExtensions.x-emit-default-value}}{{#required}}true{{/required}}{{^required}}{{#isBoolean}}true{{/isBoolean}}{{^isBoolean}}{{#isNullable}}true{{/isNullable}}{{^isNullable}}false{{/isNullable}}{{/isBoolean}}{{/required}}{{/vendorExtensions.x-emit-default-value}})]
+        [DataMember(Name = "{{baseName}}"{{#required}}, IsRequired = true{{/required}}, EmitDefaultValue = {{#isNullable}}true{{/isNullable}}{{^isNullable}}{{#vendorExtensions.x-is-value-type}}true{{/vendorExtensions.x-is-value-type}}{{^vendorExtensions.x-is-value-type}}false{{/vendorExtensions.x-is-value-type}}{{/isNullable}})]
         {{#deprecated}}
         [Obsolete]
         {{/deprecated}}
-        public {{{complexType}}}{{^complexType}}{{{datatypeWithEnum}}}{{/complexType}}{{^isContainer}}{{^required}}?{{/required}}{{/isContainer}} {{name}}
+        public {{{complexType}}}{{^complexType}}{{{datatypeWithEnum}}}{{/complexType}}{{#nullableReferenceTypes}}{{^isContainer}}{{^required}}{{#isNullable}}?{{/isNullable}}{{/required}}{{/isContainer}}{{#isContainer}}{{#isNullable}}{{^required}}?{{/required}}{{/isNullable}}{{/isContainer}}{{/nullableReferenceTypes}} {{name}}
         {
             get{ return _{{name}};}
             set
@@ -97,7 +97,7 @@
                 _flag{{name}} = true;
             }
         }
-        private {{{complexType}}}{{^complexType}}{{{datatypeWithEnum}}}{{/complexType}}{{^isContainer}}{{^required}}?{{/required}}{{/isContainer}} _{{name}};
+        private {{{complexType}}}{{^complexType}}{{{datatypeWithEnum}}}{{/complexType}}{{#nullableReferenceTypes}}{{^isContainer}}{{^required}}{{#isNullable}}?{{/isNullable}}{{/required}}{{/isContainer}}{{#isContainer}}{{#isNullable}}{{^required}}?{{/required}}{{/isNullable}}{{/isContainer}}{{/nullableReferenceTypes}} _{{name}};
         private bool _flag{{name}};
 
         /// <summary>
@@ -223,7 +223,7 @@
         */
         {{/example}}
         {{^conditionalSerialization}}
-        [DataMember(Name = "{{baseName}}"{{#required}}, IsRequired = true{{/required}}, EmitDefaultValue = {{#vendorExtensions.x-emit-default-value}}true{{/vendorExtensions.x-emit-default-value}}{{^vendorExtensions.x-emit-default-value}}{{#required}}true{{/required}}{{^required}}{{#isBoolean}}true{{/isBoolean}}{{^isBoolean}}{{#isNullable}}true{{/isNullable}}{{^isNullable}}false{{/isNullable}}{{/isBoolean}}{{/required}}{{/vendorExtensions.x-emit-default-value}})]
+        [DataMember(Name = "{{baseName}}"{{#required}}, IsRequired = true{{/required}}, EmitDefaultValue = {{#isNullable}}true{{/isNullable}}{{^isNullable}}{{#vendorExtensions.x-is-value-type}}true{{/vendorExtensions.x-is-value-type}}{{^vendorExtensions.x-is-value-type}}false{{/vendorExtensions.x-is-value-type}}{{/isNullable}})]
         {{#isDate}}
         {{^supportsDateOnly}}
         [JsonConverter(typeof(OpenAPIDateConverter))]
@@ -232,7 +232,7 @@
         {{#deprecated}}
         [Obsolete]
         {{/deprecated}}
-        public {{{dataType}}} {{name}} { get; {{#isReadOnly}}private {{/isReadOnly}}set; }
+        public {{{dataType}}}{{#nullableReferenceTypes}}{{^isContainer}}{{^required}}{{#isNullable}}?{{/isNullable}}{{/required}}{{/isContainer}}{{#isContainer}}{{#isNullable}}{{^required}}?{{/required}}{{/isNullable}}{{/isContainer}}{{/nullableReferenceTypes}} {{name}} { get; {{#isReadOnly}}private {{/isReadOnly}}set; }
 
         {{#isReadOnly}}
         /// <summary>
@@ -247,14 +247,14 @@
         {{/conditionalSerialization}}
         {{#conditionalSerialization}}
         {{#isReadOnly}}
-        [DataMember(Name = "{{baseName}}"{{#required}}, IsRequired = true{{/required}}, EmitDefaultValue = {{#vendorExtensions.x-emit-default-value}}true{{/vendorExtensions.x-emit-default-value}}{{^vendorExtensions.x-emit-default-value}}{{#required}}true{{/required}}{{^required}}{{#isBoolean}}true{{/isBoolean}}{{^isBoolean}}{{#isNullable}}true{{/isNullable}}{{^isNullable}}false{{/isNullable}}{{/isBoolean}}{{/required}}{{/vendorExtensions.x-emit-default-value}})]
+        [DataMember(Name = "{{baseName}}"{{#required}}, IsRequired = true{{/required}}, EmitDefaultValue = {{#isNullable}}true{{/isNullable}}{{^isNullable}}{{#vendorExtensions.x-is-value-type}}true{{/vendorExtensions.x-is-value-type}}{{^vendorExtensions.x-is-value-type}}false{{/vendorExtensions.x-is-value-type}}{{/isNullable}})]
         {{#isDate}}
         [JsonConverter(typeof(OpenAPIDateConverter))]
         {{/isDate}}
         {{#deprecated}}
         [Obsolete]
         {{/deprecated}}
-        public {{{dataType}}} {{name}} { get; private set; }
+        public {{{dataType}}}{{#nullableReferenceTypes}}{{^isContainer}}{{^required}}{{#isNullable}}?{{/isNullable}}{{/required}}{{/isContainer}}{{#isContainer}}{{#isNullable}}{{^required}}?{{/required}}{{/isNullable}}{{/isContainer}}{{/nullableReferenceTypes}} {{name}} { get; private set; }
 
         /// <summary>
         /// Returns false as {{name}} should not be serialized given that it's read-only.
@@ -269,7 +269,7 @@
         {{#isDate}}
         [JsonConverter(typeof(OpenAPIDateConverter))]
         {{/isDate}}
-        [DataMember(Name = "{{baseName}}"{{#required}}, IsRequired = true{{/required}}, EmitDefaultValue = {{#vendorExtensions.x-emit-default-value}}true{{/vendorExtensions.x-emit-default-value}}{{^vendorExtensions.x-emit-default-value}}{{#required}}true{{/required}}{{^required}}{{#isBoolean}}true{{/isBoolean}}{{^isBoolean}}{{#isNullable}}true{{/isNullable}}{{^isNullable}}false{{/isNullable}}{{/isBoolean}}{{/required}}{{/vendorExtensions.x-emit-default-value}})]
+        [DataMember(Name = "{{baseName}}"{{#required}}, IsRequired = true{{/required}}, EmitDefaultValue = {{#isNullable}}true{{/isNullable}}{{^isNullable}}{{#vendorExtensions.x-is-value-type}}true{{/vendorExtensions.x-is-value-type}}{{^vendorExtensions.x-is-value-type}}false{{/vendorExtensions.x-is-value-type}}{{/isNullable}})]
         {{#deprecated}}
         [Obsolete]
         {{/deprecated}}
diff --git a/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Category.cs b/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Category.cs
index d38d7b9c68d..d38664dd6e7 100644
--- a/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Category.cs
+++ b/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Category.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>1</example>
         */
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/DefaultValue.cs b/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/DefaultValue.cs
index 714405059c4..2489d5f5112 100644
--- a/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/DefaultValue.cs
+++ b/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/DefaultValue.cs
@@ -114,19 +114,19 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets ArrayStringNullable
         /// </summary>
         [DataMember(Name = "array_string_nullable", EmitDefaultValue = true)]
-        public List<string> ArrayStringNullable { get; set; }
+        public List<string>? ArrayStringNullable { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayStringExtensionNullable
         /// </summary>
         [DataMember(Name = "array_string_extension_nullable", EmitDefaultValue = true)]
-        public List<string> ArrayStringExtensionNullable { get; set; }
+        public List<string>? ArrayStringExtensionNullable { get; set; }
 
         /// <summary>
         /// Gets or Sets StringNullable
         /// </summary>
         [DataMember(Name = "string_nullable", EmitDefaultValue = true)]
-        public string StringNullable { get; set; }
+        public string? StringNullable { get; set; }
 
         /// <summary>
         /// Returns the string presentation of the object
diff --git a/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/NumberPropertiesOnly.cs b/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/NumberPropertiesOnly.cs
index 385596a2a36..60cc5269ee6 100644
--- a/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/NumberPropertiesOnly.cs
+++ b/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/NumberPropertiesOnly.cs
@@ -48,19 +48,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Number
         /// </summary>
-        [DataMember(Name = "number", EmitDefaultValue = false)]
+        [DataMember(Name = "number", EmitDefaultValue = true)]
         public decimal Number { get; set; }
 
         /// <summary>
         /// Gets or Sets Float
         /// </summary>
-        [DataMember(Name = "float", EmitDefaultValue = false)]
+        [DataMember(Name = "float", EmitDefaultValue = true)]
         public float Float { get; set; }
 
         /// <summary>
         /// Gets or Sets Double
         /// </summary>
-        [DataMember(Name = "double", EmitDefaultValue = false)]
+        [DataMember(Name = "double", EmitDefaultValue = true)]
         public double Double { get; set; }
 
         /// <summary>
diff --git a/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Pet.cs b/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Pet.cs
index d3f322a33a2..2610bda163f 100644
--- a/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Pet.cs
+++ b/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Pet.cs
@@ -63,8 +63,8 @@ namespace Org.OpenAPITools.Model
         /// pet status in the store
         /// </summary>
         /// <value>pet status in the store</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Pet" /> class.
         /// </summary>
@@ -105,7 +105,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>10</example>
         */
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -114,7 +114,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>doggie</example>
         */
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
@@ -126,7 +126,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets PhotoUrls
         /// </summary>
-        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = false)]
         public List<string> PhotoUrls { get; set; }
 
         /// <summary>
diff --git a/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Query.cs b/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Query.cs
index 8f4c27048fb..b67ba70fdd9 100644
--- a/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Query.cs
+++ b/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Query.cs
@@ -72,7 +72,7 @@ namespace Org.OpenAPITools.Model
         /// Query
         /// </summary>
         /// <value>Query</value>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Tag.cs b/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Tag.cs
index 71470730832..e3284778499 100644
--- a/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Tag.cs
+++ b/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Tag.cs
@@ -46,7 +46,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter.cs b/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter.cs
index 4d83efa5736..8e71432178b 100644
--- a/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter.cs
+++ b/samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter.cs
@@ -65,7 +65,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>1</example>
         */
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/others/csharp-complex-files/src/Org.OpenAPITools/Model/MultipartMixedRequest.cs b/samples/client/others/csharp-complex-files/src/Org.OpenAPITools/Model/MultipartMixedRequest.cs
index 17a5fc53f5e..094441602cf 100644
--- a/samples/client/others/csharp-complex-files/src/Org.OpenAPITools/Model/MultipartMixedRequest.cs
+++ b/samples/client/others/csharp-complex-files/src/Org.OpenAPITools/Model/MultipartMixedRequest.cs
@@ -73,7 +73,7 @@ namespace Org.OpenAPITools.Model
         /// a file
         /// </summary>
         /// <value>a file</value>
-        [DataMember(Name = "file", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "file", IsRequired = true, EmitDefaultValue = false)]
         public System.IO.Stream File { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs
index 35cb11b2590..8229afa5cfa 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs
@@ -73,7 +73,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets Anytype1
         /// </summary>
         [DataMember(Name = "anytype_1", EmitDefaultValue = true)]
-        public Object Anytype1 { get; set; }
+        public Object? Anytype1 { get; set; }
 
         /// <summary>
         /// Gets or Sets MapWithUndeclaredPropertiesAnytype1
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Animal.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Animal.cs
index d9839dfdb7a..0043ebccaad 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Animal.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Animal.cs
@@ -66,7 +66,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
index ac0d3f572d4..dba9b532c07 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
@@ -50,7 +50,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Code
         /// </summary>
-        [DataMember(Name = "code", EmitDefaultValue = false)]
+        [DataMember(Name = "code", EmitDefaultValue = true)]
         public int Code { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
index a21b749c062..425e633a1c8 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
@@ -57,7 +57,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Cultivar
         /// </summary>
-        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = false)]
         public string Cultivar { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Banana.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Banana.cs
index caa5bbd6354..b31a568111c 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Banana.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Banana.cs
@@ -46,7 +46,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets LengthCm
         /// </summary>
-        [DataMember(Name = "lengthCm", EmitDefaultValue = false)]
+        [DataMember(Name = "lengthCm", EmitDefaultValue = true)]
         public decimal LengthCm { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
index 3c9d8fddeb6..4d8ed418f42 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
@@ -59,7 +59,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Category.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Category.cs
index b4f5b1831b1..285cff71b34 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Category.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Category.cs
@@ -61,13 +61,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
index e6bc8973e21..f1238f5fd8a 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
@@ -66,13 +66,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs
index bb10b291e82..bca3677647a 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs
@@ -81,7 +81,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets CopyActivitytt
         /// </summary>
-        [DataMember(Name = "copyActivitytt", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "copyActivitytt", IsRequired = true, EmitDefaultValue = false)]
         public string CopyActivitytt { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
index 047100d98c2..31b0fb4f396 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
@@ -59,7 +59,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Drawing.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Drawing.cs
index 575712f265f..33f9b9f7ead 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Drawing.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Drawing.cs
@@ -59,13 +59,13 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets ShapeOrNull
         /// </summary>
         [DataMember(Name = "shapeOrNull", EmitDefaultValue = true)]
-        public ShapeOrNull ShapeOrNull { get; set; }
+        public ShapeOrNull? ShapeOrNull { get; set; }
 
         /// <summary>
         /// Gets or Sets NullableShape
         /// </summary>
         [DataMember(Name = "nullableShape", EmitDefaultValue = true)]
-        public NullableShape NullableShape { get; set; }
+        public NullableShape? NullableShape { get; set; }
 
         /// <summary>
         /// Gets or Sets Shapes
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs
index 52bb01e48a3..bbb08bd8e70 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs
@@ -62,7 +62,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Schema
         /// </summary>
-        [DataMember(Name = "$schema", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "$schema", IsRequired = true, EmitDefaultValue = false)]
         public string Schema { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
index 8c561798337..52e2aabfffc 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
@@ -56,8 +56,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustSymbol
         /// </summary>
-        [DataMember(Name = "just_symbol", EmitDefaultValue = false)]
-        public JustSymbolEnum? JustSymbol { get; set; }
+        [DataMember(Name = "just_symbol", EmitDefaultValue = true)]
+        public JustSymbolEnum JustSymbol { get; set; }
         /// <summary>
         /// Defines ArrayEnum
         /// </summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
index c8bb688e948..45dfddd57c7 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
@@ -92,8 +92,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumString
         /// </summary>
-        [DataMember(Name = "enum_string", EmitDefaultValue = false)]
-        public EnumStringEnum? EnumString { get; set; }
+        [DataMember(Name = "enum_string", EmitDefaultValue = true)]
+        public EnumStringEnum EnumString { get; set; }
         /// <summary>
         /// Defines EnumStringRequired
         /// </summary>
@@ -175,8 +175,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumInteger
         /// </summary>
-        [DataMember(Name = "enum_integer", EmitDefaultValue = false)]
-        public EnumIntegerEnum? EnumInteger { get; set; }
+        [DataMember(Name = "enum_integer", EmitDefaultValue = true)]
+        public EnumIntegerEnum EnumInteger { get; set; }
         /// <summary>
         /// Defines EnumIntegerOnly
         /// </summary>
@@ -197,8 +197,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "enum_integer_only", EmitDefaultValue = false)]
-        public EnumIntegerOnlyEnum? EnumIntegerOnly { get; set; }
+        [DataMember(Name = "enum_integer_only", EmitDefaultValue = true)]
+        public EnumIntegerOnlyEnum EnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines EnumNumber
         /// </summary>
@@ -222,8 +222,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumNumber
         /// </summary>
-        [DataMember(Name = "enum_number", EmitDefaultValue = false)]
-        public EnumNumberEnum? EnumNumber { get; set; }
+        [DataMember(Name = "enum_number", EmitDefaultValue = true)]
+        public EnumNumberEnum EnumNumber { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnum
@@ -234,20 +234,20 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets OuterEnumInteger
         /// </summary>
-        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = false)]
-        public OuterEnumInteger? OuterEnumInteger { get; set; }
+        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = true)]
+        public OuterEnumInteger OuterEnumInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? OuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue OuterEnumDefaultValue { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumIntegerDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumIntegerDefaultValue? OuterEnumIntegerDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumIntegerDefaultValue OuterEnumIntegerDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="EnumTest" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
index dd4afe27da5..60dcb4f0446 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
@@ -66,13 +66,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
index 70e020f818c..dd24833cbac 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
@@ -114,61 +114,61 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Integer
         /// </summary>
-        [DataMember(Name = "integer", EmitDefaultValue = false)]
+        [DataMember(Name = "integer", EmitDefaultValue = true)]
         public int Integer { get; set; }
 
         /// <summary>
         /// Gets or Sets Int32
         /// </summary>
-        [DataMember(Name = "int32", EmitDefaultValue = false)]
+        [DataMember(Name = "int32", EmitDefaultValue = true)]
         public int Int32 { get; set; }
 
         /// <summary>
         /// Gets or Sets Int32Range
         /// </summary>
-        [DataMember(Name = "int32Range", EmitDefaultValue = false)]
+        [DataMember(Name = "int32Range", EmitDefaultValue = true)]
         public int Int32Range { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64Positive
         /// </summary>
-        [DataMember(Name = "int64Positive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64Positive", EmitDefaultValue = true)]
         public long Int64Positive { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64Negative
         /// </summary>
-        [DataMember(Name = "int64Negative", EmitDefaultValue = false)]
+        [DataMember(Name = "int64Negative", EmitDefaultValue = true)]
         public long Int64Negative { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64PositiveExclusive
         /// </summary>
-        [DataMember(Name = "int64PositiveExclusive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64PositiveExclusive", EmitDefaultValue = true)]
         public long Int64PositiveExclusive { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64NegativeExclusive
         /// </summary>
-        [DataMember(Name = "int64NegativeExclusive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64NegativeExclusive", EmitDefaultValue = true)]
         public long Int64NegativeExclusive { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedInteger
         /// </summary>
-        [DataMember(Name = "unsigned_integer", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_integer", EmitDefaultValue = true)]
         public uint UnsignedInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64
         /// </summary>
-        [DataMember(Name = "int64", EmitDefaultValue = false)]
+        [DataMember(Name = "int64", EmitDefaultValue = true)]
         public long Int64 { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedLong
         /// </summary>
-        [DataMember(Name = "unsigned_long", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_long", EmitDefaultValue = true)]
         public ulong UnsignedLong { get; set; }
 
         /// <summary>
@@ -180,19 +180,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Float
         /// </summary>
-        [DataMember(Name = "float", EmitDefaultValue = false)]
+        [DataMember(Name = "float", EmitDefaultValue = true)]
         public float Float { get; set; }
 
         /// <summary>
         /// Gets or Sets Double
         /// </summary>
-        [DataMember(Name = "double", EmitDefaultValue = false)]
+        [DataMember(Name = "double", EmitDefaultValue = true)]
         public double Double { get; set; }
 
         /// <summary>
         /// Gets or Sets Decimal
         /// </summary>
-        [DataMember(Name = "decimal", EmitDefaultValue = false)]
+        [DataMember(Name = "decimal", EmitDefaultValue = true)]
         public decimal Decimal { get; set; }
 
         /// <summary>
@@ -204,7 +204,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Byte
         /// </summary>
-        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = false)]
         public byte[] Byte { get; set; }
 
         /// <summary>
@@ -219,7 +219,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>Sun Feb 02 00:00:00 UTC 2020</example>
         */
-        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = false)]
         public DateOnly Date { get; set; }
 
         /// <summary>
@@ -243,7 +243,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Password
         /// </summary>
-        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = false)]
         public string Password { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
index f3d60eb6a79..e0890e8a5b5 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
@@ -63,7 +63,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets PetType
         /// </summary>
-        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = false)]
         public string PetType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/HealthCheckResult.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/HealthCheckResult.cs
index c1791fadad7..62ec2a7179d 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/HealthCheckResult.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/HealthCheckResult.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NullableMessage
         /// </summary>
         [DataMember(Name = "NullableMessage", EmitDefaultValue = true)]
-        public string NullableMessage { get; set; }
+        public string? NullableMessage { get; set; }
 
         /// <summary>
         /// Gets or Sets additional properties
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
index 0e2b942360c..43b2678067d 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
@@ -62,13 +62,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
index e3aad5bb540..277f6669653 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
@@ -48,7 +48,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", EmitDefaultValue = false)]
+        [DataMember(Name = "name", EmitDefaultValue = true)]
         public int Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Name.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Name.cs
index 03994dbe545..f2b41a0ed39 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Name.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Name.cs
@@ -62,7 +62,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SnakeCase
         /// </summary>
-        [DataMember(Name = "snake_case", EmitDefaultValue = false)]
+        [DataMember(Name = "snake_case", EmitDefaultValue = true)]
         public int SnakeCase { get; private set; }
 
         /// <summary>
@@ -82,7 +82,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Var123Number
         /// </summary>
-        [DataMember(Name = "123Number", EmitDefaultValue = false)]
+        [DataMember(Name = "123Number", EmitDefaultValue = true)]
         public int Var123Number { get; private set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
index 5246937f6e6..100db80d2fc 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
@@ -67,7 +67,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets AObjVariableobject
         /// </summary>
-        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = false)]
         public List<Dictionary<string, Object>> AObjVariableobject { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs
index a664857f3d3..b7971d1af2e 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs
@@ -69,49 +69,49 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets IntegerProp
         /// </summary>
         [DataMember(Name = "integer_prop", EmitDefaultValue = true)]
-        public int? IntegerProp { get; set; }
+        public int?? IntegerProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NumberProp
         /// </summary>
         [DataMember(Name = "number_prop", EmitDefaultValue = true)]
-        public decimal? NumberProp { get; set; }
+        public decimal?? NumberProp { get; set; }
 
         /// <summary>
         /// Gets or Sets BooleanProp
         /// </summary>
         [DataMember(Name = "boolean_prop", EmitDefaultValue = true)]
-        public bool? BooleanProp { get; set; }
+        public bool?? BooleanProp { get; set; }
 
         /// <summary>
         /// Gets or Sets StringProp
         /// </summary>
         [DataMember(Name = "string_prop", EmitDefaultValue = true)]
-        public string StringProp { get; set; }
+        public string? StringProp { get; set; }
 
         /// <summary>
         /// 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
         /// </summary>
         [DataMember(Name = "datetime_prop", EmitDefaultValue = true)]
-        public DateTime? DatetimeProp { get; set; }
+        public DateTime?? DatetimeProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayNullableProp
         /// </summary>
         [DataMember(Name = "array_nullable_prop", EmitDefaultValue = true)]
-        public List<Object> ArrayNullableProp { get; set; }
+        public List<Object>? ArrayNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayAndItemsNullableProp
         /// </summary>
         [DataMember(Name = "array_and_items_nullable_prop", EmitDefaultValue = true)]
-        public List<Object> ArrayAndItemsNullableProp { get; set; }
+        public List<Object>? ArrayAndItemsNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayItemsNullable
@@ -123,13 +123,13 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets ObjectNullableProp
         /// </summary>
         [DataMember(Name = "object_nullable_prop", EmitDefaultValue = true)]
-        public Dictionary<string, Object> ObjectNullableProp { get; set; }
+        public Dictionary<string, Object>? ObjectNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ObjectAndItemsNullableProp
         /// </summary>
         [DataMember(Name = "object_and_items_nullable_prop", EmitDefaultValue = true)]
-        public Dictionary<string, Object> ObjectAndItemsNullableProp { get; set; }
+        public Dictionary<string, Object>? ObjectAndItemsNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ObjectItemsNullable
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NullableGuidClass.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NullableGuidClass.cs
index b3e90dc6211..d4ce8788abe 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NullableGuidClass.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NullableGuidClass.cs
@@ -50,7 +50,7 @@ namespace Org.OpenAPITools.Model
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
         [DataMember(Name = "uuid", EmitDefaultValue = true)]
-        public Guid? Uuid { get; set; }
+        public Guid?? Uuid { get; set; }
 
         /// <summary>
         /// Gets or Sets additional properties
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
index 7370cf5f4f6..83ebab9ad0c 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustNumber
         /// </summary>
-        [DataMember(Name = "JustNumber", EmitDefaultValue = false)]
+        [DataMember(Name = "JustNumber", EmitDefaultValue = true)]
         public decimal JustNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
index ac765f067af..76b85ab87a7 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         [Obsolete]
         public decimal Id { get; set; }
 
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Order.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Order.cs
index 25b3fe0b278..5bea91b548a 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Order.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Order.cs
@@ -64,8 +64,8 @@ namespace Org.OpenAPITools.Model
         /// Order Status
         /// </summary>
         /// <value>Order Status</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Order" /> class.
         /// </summary>
@@ -89,19 +89,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets PetId
         /// </summary>
-        [DataMember(Name = "petId", EmitDefaultValue = false)]
+        [DataMember(Name = "petId", EmitDefaultValue = true)]
         public long PetId { get; set; }
 
         /// <summary>
         /// Gets or Sets Quantity
         /// </summary>
-        [DataMember(Name = "quantity", EmitDefaultValue = false)]
+        [DataMember(Name = "quantity", EmitDefaultValue = true)]
         public int Quantity { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
index 5d5dfb6d34f..661b25f7ac3 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
@@ -50,7 +50,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets MyNumber
         /// </summary>
-        [DataMember(Name = "my_number", EmitDefaultValue = false)]
+        [DataMember(Name = "my_number", EmitDefaultValue = true)]
         public decimal MyNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Pet.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Pet.cs
index dcb43332574..375d78775c6 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Pet.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Pet.cs
@@ -64,8 +64,8 @@ namespace Org.OpenAPITools.Model
         /// pet status in the store
         /// </summary>
         /// <value>pet status in the store</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Pet" /> class.
         /// </summary>
@@ -107,7 +107,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -122,13 +122,13 @@ namespace Org.OpenAPITools.Model
         /*
         <example>doggie</example>
         */
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
         /// Gets or Sets PhotoUrls
         /// </summary>
-        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = false)]
         public List<string> PhotoUrls { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
index f0f16774eff..611956a938f 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
@@ -59,7 +59,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
index f14b947cd74..2dd45cc3643 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
@@ -119,8 +119,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumInteger
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerEnum? NotrequiredNotnullableEnumInteger { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerEnum NotrequiredNotnullableEnumInteger { get; set; }
         /// <summary>
         /// Defines RequiredNullableEnumIntegerOnly
         /// </summary>
@@ -209,8 +209,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerOnlyEnum? NotrequiredNotnullableEnumIntegerOnly { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerOnlyEnum NotrequiredNotnullableEnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines RequiredNotnullableEnumString
         /// </summary>
@@ -453,8 +453,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumString
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumStringEnum? NotrequiredNotnullableEnumString { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumStringEnum NotrequiredNotnullableEnumString { get; set; }
 
         /// <summary>
         /// Gets or Sets RequiredNullableOuterEnumDefaultValue
@@ -477,8 +477,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableOuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="RequiredClass" /> class.
         /// </summary>
@@ -644,12 +644,12 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotRequiredNullableIntegerProp
         /// </summary>
         [DataMember(Name = "not_required_nullable_integer_prop", EmitDefaultValue = true)]
-        public int? NotRequiredNullableIntegerProp { get; set; }
+        public int?? NotRequiredNullableIntegerProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotRequiredNotnullableintegerProp
         /// </summary>
-        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = false)]
+        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = true)]
         public int NotRequiredNotnullableintegerProp { get; set; }
 
         /// <summary>
@@ -661,14 +661,14 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableStringProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = false)]
         public string RequiredNotnullableStringProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNullableStringProp
         /// </summary>
         [DataMember(Name = "notrequired_nullable_string_prop", EmitDefaultValue = true)]
-        public string NotrequiredNullableStringProp { get; set; }
+        public string? NotrequiredNullableStringProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableStringProp
@@ -692,7 +692,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableBooleanProp
         /// </summary>
         [DataMember(Name = "notrequired_nullable_boolean_prop", EmitDefaultValue = true)]
-        public bool? NotrequiredNullableBooleanProp { get; set; }
+        public bool?? NotrequiredNullableBooleanProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableBooleanProp
@@ -709,14 +709,14 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotNullableDateProp
         /// </summary>
-        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateOnly RequiredNotNullableDateProp { get; set; }
 
         /// <summary>
         /// 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
@@ -727,7 +727,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableDatetimeProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateTime RequiredNotnullableDatetimeProp { get; set; }
 
         /// <summary>
@@ -740,7 +740,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableDatetimeProp
         /// </summary>
         [DataMember(Name = "notrequired_nullable_datetime_prop", EmitDefaultValue = true)]
-        public DateTime? NotrequiredNullableDatetimeProp { get; set; }
+        public DateTime?? NotrequiredNullableDatetimeProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableDatetimeProp
@@ -763,7 +763,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
-        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = false)]
         public Guid RequiredNotnullableUuid { get; set; }
 
         /// <summary>
@@ -773,7 +773,7 @@ namespace Org.OpenAPITools.Model
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
         [DataMember(Name = "notrequired_nullable_uuid", EmitDefaultValue = true)]
-        public Guid? NotrequiredNullableUuid { get; set; }
+        public Guid?? NotrequiredNullableUuid { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableUuid
@@ -793,14 +793,14 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableArrayOfString
         /// </summary>
-        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = false)]
         public List<string> RequiredNotnullableArrayOfString { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNullableArrayOfString
         /// </summary>
         [DataMember(Name = "notrequired_nullable_array_of_string", EmitDefaultValue = true)]
-        public List<string> NotrequiredNullableArrayOfString { get; set; }
+        public List<string>? NotrequiredNullableArrayOfString { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableArrayOfString
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Return.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Return.cs
index 533ce598cc8..49d7b73e1bc 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Return.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Return.cs
@@ -70,13 +70,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets VarReturn
         /// </summary>
-        [DataMember(Name = "return", EmitDefaultValue = false)]
+        [DataMember(Name = "return", EmitDefaultValue = true)]
         public int VarReturn { get; set; }
 
         /// <summary>
         /// Gets or Sets Lock
         /// </summary>
-        [DataMember(Name = "lock", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "lock", IsRequired = true, EmitDefaultValue = false)]
         public string Lock { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
index 5d867c7256f..7dd539094ba 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
@@ -66,13 +66,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
index ca231858e2f..fb3aa1d6197 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
@@ -59,7 +59,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
index 5c5f3b24b05..4f368488734 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
@@ -66,13 +66,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
index d89637d463a..c18feb75fbd 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
@@ -48,7 +48,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SpecialPropertyName
         /// </summary>
-        [DataMember(Name = "$special[property.name]", EmitDefaultValue = false)]
+        [DataMember(Name = "$special[property.name]", EmitDefaultValue = true)]
         public long SpecialPropertyName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Tag.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Tag.cs
index 75be41dff9c..efab17054c6 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Tag.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Tag.cs
@@ -48,7 +48,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
index 0f5a61d0df5..af21c7ea699 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
@@ -59,7 +59,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/User.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/User.cs
index 910903ecfb5..eaec2b84b6e 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/User.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/User.cs
@@ -68,7 +68,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -111,7 +111,7 @@ namespace Org.OpenAPITools.Model
         /// User Status
         /// </summary>
         /// <value>User Status</value>
-        [DataMember(Name = "userStatus", EmitDefaultValue = false)]
+        [DataMember(Name = "userStatus", EmitDefaultValue = true)]
         public int UserStatus { get; set; }
 
         /// <summary>
@@ -126,21 +126,21 @@ namespace Org.OpenAPITools.Model
         /// </summary>
         /// <value>test code generation for nullable objects. Value must be a map of strings to values or the &#39;null&#39; value.</value>
         [DataMember(Name = "objectWithNoDeclaredPropsNullable", EmitDefaultValue = true)]
-        public Object ObjectWithNoDeclaredPropsNullable { get; set; }
+        public Object? ObjectWithNoDeclaredPropsNullable { get; set; }
 
         /// <summary>
         /// test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. See https://github.com/OAI/OpenAPI-Specification/issues/1389
         /// </summary>
         /// <value>test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. See https://github.com/OAI/OpenAPI-Specification/issues/1389</value>
         [DataMember(Name = "anyTypeProp", EmitDefaultValue = true)]
-        public Object AnyTypeProp { get; set; }
+        public Object? AnyTypeProp { get; set; }
 
         /// <summary>
         /// test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. The &#39;nullable&#39; attribute does not change the allowed values.
         /// </summary>
         /// <value>test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. The &#39;nullable&#39; attribute does not change the allowed values.</value>
         [DataMember(Name = "anyTypePropNullable", EmitDefaultValue = true)]
-        public Object AnyTypePropNullable { get; set; }
+        public Object? AnyTypePropNullable { get; set; }
 
         /// <summary>
         /// Gets or Sets additional properties
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Whale.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Whale.cs
index e49f7867fdd..b54a43611c4 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Whale.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Whale.cs
@@ -75,7 +75,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Zebra.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
index 34775905ac9..2cc9945a03c 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
@@ -62,8 +62,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Type
         /// </summary>
-        [DataMember(Name = "type", EmitDefaultValue = false)]
-        public TypeEnum? Type { get; set; }
+        [DataMember(Name = "type", EmitDefaultValue = true)]
+        public TypeEnum Type { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Zebra" /> class.
         /// </summary>
@@ -92,7 +92,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
index 8e919c1af84..78d92d5de4a 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
@@ -56,8 +56,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ZeroBasedEnum
         /// </summary>
-        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = false)]
-        public ZeroBasedEnumEnum? ZeroBasedEnum { get; set; }
+        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = true)]
+        public ZeroBasedEnumEnum ZeroBasedEnum { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="ZeroBasedEnumClass" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Animal.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Animal.cs
index d9839dfdb7a..0043ebccaad 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Animal.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Animal.cs
@@ -66,7 +66,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
index ac0d3f572d4..dba9b532c07 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
@@ -50,7 +50,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Code
         /// </summary>
-        [DataMember(Name = "code", EmitDefaultValue = false)]
+        [DataMember(Name = "code", EmitDefaultValue = true)]
         public int Code { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
index a21b749c062..425e633a1c8 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
@@ -57,7 +57,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Cultivar
         /// </summary>
-        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = false)]
         public string Cultivar { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Banana.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Banana.cs
index caa5bbd6354..b31a568111c 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Banana.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Banana.cs
@@ -46,7 +46,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets LengthCm
         /// </summary>
-        [DataMember(Name = "lengthCm", EmitDefaultValue = false)]
+        [DataMember(Name = "lengthCm", EmitDefaultValue = true)]
         public decimal LengthCm { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
index 3c9d8fddeb6..4d8ed418f42 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
@@ -59,7 +59,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Category.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Category.cs
index b4f5b1831b1..285cff71b34 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Category.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Category.cs
@@ -61,13 +61,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
index e6bc8973e21..f1238f5fd8a 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
@@ -66,13 +66,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs
index bb10b291e82..bca3677647a 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs
@@ -81,7 +81,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets CopyActivitytt
         /// </summary>
-        [DataMember(Name = "copyActivitytt", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "copyActivitytt", IsRequired = true, EmitDefaultValue = false)]
         public string CopyActivitytt { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
index 047100d98c2..31b0fb4f396 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
@@ -59,7 +59,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs
index 52bb01e48a3..bbb08bd8e70 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs
@@ -62,7 +62,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Schema
         /// </summary>
-        [DataMember(Name = "$schema", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "$schema", IsRequired = true, EmitDefaultValue = false)]
         public string Schema { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
index 8c561798337..52e2aabfffc 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
@@ -56,8 +56,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustSymbol
         /// </summary>
-        [DataMember(Name = "just_symbol", EmitDefaultValue = false)]
-        public JustSymbolEnum? JustSymbol { get; set; }
+        [DataMember(Name = "just_symbol", EmitDefaultValue = true)]
+        public JustSymbolEnum JustSymbol { get; set; }
         /// <summary>
         /// Defines ArrayEnum
         /// </summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
index c8bb688e948..87f1019019a 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
@@ -92,8 +92,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumString
         /// </summary>
-        [DataMember(Name = "enum_string", EmitDefaultValue = false)]
-        public EnumStringEnum? EnumString { get; set; }
+        [DataMember(Name = "enum_string", EmitDefaultValue = true)]
+        public EnumStringEnum EnumString { get; set; }
         /// <summary>
         /// Defines EnumStringRequired
         /// </summary>
@@ -175,8 +175,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumInteger
         /// </summary>
-        [DataMember(Name = "enum_integer", EmitDefaultValue = false)]
-        public EnumIntegerEnum? EnumInteger { get; set; }
+        [DataMember(Name = "enum_integer", EmitDefaultValue = true)]
+        public EnumIntegerEnum EnumInteger { get; set; }
         /// <summary>
         /// Defines EnumIntegerOnly
         /// </summary>
@@ -197,8 +197,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "enum_integer_only", EmitDefaultValue = false)]
-        public EnumIntegerOnlyEnum? EnumIntegerOnly { get; set; }
+        [DataMember(Name = "enum_integer_only", EmitDefaultValue = true)]
+        public EnumIntegerOnlyEnum EnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines EnumNumber
         /// </summary>
@@ -222,32 +222,32 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumNumber
         /// </summary>
-        [DataMember(Name = "enum_number", EmitDefaultValue = false)]
-        public EnumNumberEnum? EnumNumber { get; set; }
+        [DataMember(Name = "enum_number", EmitDefaultValue = true)]
+        public EnumNumberEnum EnumNumber { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnum
         /// </summary>
         [DataMember(Name = "outerEnum", EmitDefaultValue = true)]
-        public OuterEnum? OuterEnum { get; set; }
+        public OuterEnum OuterEnum { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumInteger
         /// </summary>
-        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = false)]
-        public OuterEnumInteger? OuterEnumInteger { get; set; }
+        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = true)]
+        public OuterEnumInteger OuterEnumInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? OuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue OuterEnumDefaultValue { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumIntegerDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumIntegerDefaultValue? OuterEnumIntegerDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumIntegerDefaultValue OuterEnumIntegerDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="EnumTest" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
index dd4afe27da5..60dcb4f0446 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
@@ -66,13 +66,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
index 0730a228208..096e0969f8a 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
@@ -114,61 +114,61 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Integer
         /// </summary>
-        [DataMember(Name = "integer", EmitDefaultValue = false)]
+        [DataMember(Name = "integer", EmitDefaultValue = true)]
         public int Integer { get; set; }
 
         /// <summary>
         /// Gets or Sets Int32
         /// </summary>
-        [DataMember(Name = "int32", EmitDefaultValue = false)]
+        [DataMember(Name = "int32", EmitDefaultValue = true)]
         public int Int32 { get; set; }
 
         /// <summary>
         /// Gets or Sets Int32Range
         /// </summary>
-        [DataMember(Name = "int32Range", EmitDefaultValue = false)]
+        [DataMember(Name = "int32Range", EmitDefaultValue = true)]
         public int Int32Range { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64Positive
         /// </summary>
-        [DataMember(Name = "int64Positive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64Positive", EmitDefaultValue = true)]
         public long Int64Positive { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64Negative
         /// </summary>
-        [DataMember(Name = "int64Negative", EmitDefaultValue = false)]
+        [DataMember(Name = "int64Negative", EmitDefaultValue = true)]
         public long Int64Negative { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64PositiveExclusive
         /// </summary>
-        [DataMember(Name = "int64PositiveExclusive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64PositiveExclusive", EmitDefaultValue = true)]
         public long Int64PositiveExclusive { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64NegativeExclusive
         /// </summary>
-        [DataMember(Name = "int64NegativeExclusive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64NegativeExclusive", EmitDefaultValue = true)]
         public long Int64NegativeExclusive { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedInteger
         /// </summary>
-        [DataMember(Name = "unsigned_integer", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_integer", EmitDefaultValue = true)]
         public uint UnsignedInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64
         /// </summary>
-        [DataMember(Name = "int64", EmitDefaultValue = false)]
+        [DataMember(Name = "int64", EmitDefaultValue = true)]
         public long Int64 { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedLong
         /// </summary>
-        [DataMember(Name = "unsigned_long", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_long", EmitDefaultValue = true)]
         public ulong UnsignedLong { get; set; }
 
         /// <summary>
@@ -180,19 +180,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Float
         /// </summary>
-        [DataMember(Name = "float", EmitDefaultValue = false)]
+        [DataMember(Name = "float", EmitDefaultValue = true)]
         public float Float { get; set; }
 
         /// <summary>
         /// Gets or Sets Double
         /// </summary>
-        [DataMember(Name = "double", EmitDefaultValue = false)]
+        [DataMember(Name = "double", EmitDefaultValue = true)]
         public double Double { get; set; }
 
         /// <summary>
         /// Gets or Sets Decimal
         /// </summary>
-        [DataMember(Name = "decimal", EmitDefaultValue = false)]
+        [DataMember(Name = "decimal", EmitDefaultValue = true)]
         public decimal Decimal { get; set; }
 
         /// <summary>
@@ -204,7 +204,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Byte
         /// </summary>
-        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = false)]
         public byte[] Byte { get; set; }
 
         /// <summary>
@@ -219,7 +219,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>Sun Feb 02 00:00:00 UTC 2020</example>
         */
-        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = false)]
         [JsonConverter(typeof(OpenAPIDateConverter))]
         public DateTime Date { get; set; }
 
@@ -244,7 +244,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Password
         /// </summary>
-        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = false)]
         public string Password { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
index f3d60eb6a79..e0890e8a5b5 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
@@ -63,7 +63,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets PetType
         /// </summary>
-        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = false)]
         public string PetType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
index 0e2b942360c..43b2678067d 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
@@ -62,13 +62,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
index e3aad5bb540..277f6669653 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
@@ -48,7 +48,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", EmitDefaultValue = false)]
+        [DataMember(Name = "name", EmitDefaultValue = true)]
         public int Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Name.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Name.cs
index 03994dbe545..f2b41a0ed39 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Name.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Name.cs
@@ -62,7 +62,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SnakeCase
         /// </summary>
-        [DataMember(Name = "snake_case", EmitDefaultValue = false)]
+        [DataMember(Name = "snake_case", EmitDefaultValue = true)]
         public int SnakeCase { get; private set; }
 
         /// <summary>
@@ -82,7 +82,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Var123Number
         /// </summary>
-        [DataMember(Name = "123Number", EmitDefaultValue = false)]
+        [DataMember(Name = "123Number", EmitDefaultValue = true)]
         public int Var123Number { get; private set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
index 5246937f6e6..100db80d2fc 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
@@ -67,7 +67,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets AObjVariableobject
         /// </summary>
-        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = false)]
         public List<Dictionary<string, Object>> AObjVariableobject { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
index 7370cf5f4f6..83ebab9ad0c 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustNumber
         /// </summary>
-        [DataMember(Name = "JustNumber", EmitDefaultValue = false)]
+        [DataMember(Name = "JustNumber", EmitDefaultValue = true)]
         public decimal JustNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
index ac765f067af..76b85ab87a7 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         [Obsolete]
         public decimal Id { get; set; }
 
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Order.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Order.cs
index 25b3fe0b278..5bea91b548a 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Order.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Order.cs
@@ -64,8 +64,8 @@ namespace Org.OpenAPITools.Model
         /// Order Status
         /// </summary>
         /// <value>Order Status</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Order" /> class.
         /// </summary>
@@ -89,19 +89,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets PetId
         /// </summary>
-        [DataMember(Name = "petId", EmitDefaultValue = false)]
+        [DataMember(Name = "petId", EmitDefaultValue = true)]
         public long PetId { get; set; }
 
         /// <summary>
         /// Gets or Sets Quantity
         /// </summary>
-        [DataMember(Name = "quantity", EmitDefaultValue = false)]
+        [DataMember(Name = "quantity", EmitDefaultValue = true)]
         public int Quantity { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
index 5d5dfb6d34f..661b25f7ac3 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
@@ -50,7 +50,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets MyNumber
         /// </summary>
-        [DataMember(Name = "my_number", EmitDefaultValue = false)]
+        [DataMember(Name = "my_number", EmitDefaultValue = true)]
         public decimal MyNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Pet.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Pet.cs
index dcb43332574..375d78775c6 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Pet.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Pet.cs
@@ -64,8 +64,8 @@ namespace Org.OpenAPITools.Model
         /// pet status in the store
         /// </summary>
         /// <value>pet status in the store</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Pet" /> class.
         /// </summary>
@@ -107,7 +107,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -122,13 +122,13 @@ namespace Org.OpenAPITools.Model
         /*
         <example>doggie</example>
         */
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
         /// Gets or Sets PhotoUrls
         /// </summary>
-        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = false)]
         public List<string> PhotoUrls { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
index f0f16774eff..611956a938f 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
@@ -59,7 +59,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
index c91513201c0..2defe47f289 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
@@ -98,7 +98,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableEnumInteger
         /// </summary>
         [DataMember(Name = "notrequired_nullable_enum_integer", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumIntegerEnum? NotrequiredNullableEnumInteger { get; set; }
+        public NotrequiredNullableEnumIntegerEnum NotrequiredNullableEnumInteger { get; set; }
         /// <summary>
         /// Defines NotrequiredNotnullableEnumInteger
         /// </summary>
@@ -119,8 +119,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumInteger
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerEnum? NotrequiredNotnullableEnumInteger { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerEnum NotrequiredNotnullableEnumInteger { get; set; }
         /// <summary>
         /// Defines RequiredNullableEnumIntegerOnly
         /// </summary>
@@ -188,7 +188,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableEnumIntegerOnly
         /// </summary>
         [DataMember(Name = "notrequired_nullable_enum_integer_only", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumIntegerOnlyEnum? NotrequiredNullableEnumIntegerOnly { get; set; }
+        public NotrequiredNullableEnumIntegerOnlyEnum NotrequiredNullableEnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
@@ -209,8 +209,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerOnlyEnum? NotrequiredNotnullableEnumIntegerOnly { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerOnlyEnum NotrequiredNotnullableEnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines RequiredNotnullableEnumString
         /// </summary>
@@ -393,7 +393,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableEnumString
         /// </summary>
         [DataMember(Name = "notrequired_nullable_enum_string", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumStringEnum? NotrequiredNullableEnumString { get; set; }
+        public NotrequiredNullableEnumStringEnum NotrequiredNullableEnumString { get; set; }
         /// <summary>
         /// Defines NotrequiredNotnullableEnumString
         /// </summary>
@@ -453,8 +453,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumString
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumStringEnum? NotrequiredNotnullableEnumString { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumStringEnum NotrequiredNotnullableEnumString { get; set; }
 
         /// <summary>
         /// Gets or Sets RequiredNullableOuterEnumDefaultValue
@@ -472,13 +472,13 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableOuterEnumDefaultValue
         /// </summary>
         [DataMember(Name = "notrequired_nullable_outerEnumDefaultValue", EmitDefaultValue = true)]
-        public OuterEnumDefaultValue? NotrequiredNullableOuterEnumDefaultValue { get; set; }
+        public OuterEnumDefaultValue NotrequiredNullableOuterEnumDefaultValue { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableOuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="RequiredClass" /> class.
         /// </summary>
@@ -649,7 +649,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotRequiredNotnullableintegerProp
         /// </summary>
-        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = false)]
+        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = true)]
         public int NotRequiredNotnullableintegerProp { get; set; }
 
         /// <summary>
@@ -661,7 +661,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableStringProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = false)]
         public string RequiredNotnullableStringProp { get; set; }
 
         /// <summary>
@@ -710,7 +710,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotNullableDateProp
         /// </summary>
-        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = false)]
         [JsonConverter(typeof(OpenAPIDateConverter))]
         public DateTime RequiredNotNullableDateProp { get; set; }
 
@@ -731,7 +731,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableDatetimeProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateTime RequiredNotnullableDatetimeProp { get; set; }
 
         /// <summary>
@@ -767,7 +767,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
-        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = false)]
         public Guid RequiredNotnullableUuid { get; set; }
 
         /// <summary>
@@ -797,7 +797,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableArrayOfString
         /// </summary>
-        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = false)]
         public List<string> RequiredNotnullableArrayOfString { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Return.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Return.cs
index 533ce598cc8..49d7b73e1bc 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Return.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Return.cs
@@ -70,13 +70,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets VarReturn
         /// </summary>
-        [DataMember(Name = "return", EmitDefaultValue = false)]
+        [DataMember(Name = "return", EmitDefaultValue = true)]
         public int VarReturn { get; set; }
 
         /// <summary>
         /// Gets or Sets Lock
         /// </summary>
-        [DataMember(Name = "lock", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "lock", IsRequired = true, EmitDefaultValue = false)]
         public string Lock { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
index 5d867c7256f..7dd539094ba 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
@@ -66,13 +66,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
index ca231858e2f..fb3aa1d6197 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
@@ -59,7 +59,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
index 5c5f3b24b05..4f368488734 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
@@ -66,13 +66,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
index d89637d463a..c18feb75fbd 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
@@ -48,7 +48,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SpecialPropertyName
         /// </summary>
-        [DataMember(Name = "$special[property.name]", EmitDefaultValue = false)]
+        [DataMember(Name = "$special[property.name]", EmitDefaultValue = true)]
         public long SpecialPropertyName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Tag.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Tag.cs
index 75be41dff9c..efab17054c6 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Tag.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Tag.cs
@@ -48,7 +48,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
index 0f5a61d0df5..af21c7ea699 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
@@ -59,7 +59,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/User.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/User.cs
index 910903ecfb5..febd101e10b 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/User.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/User.cs
@@ -68,7 +68,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -111,7 +111,7 @@ namespace Org.OpenAPITools.Model
         /// User Status
         /// </summary>
         /// <value>User Status</value>
-        [DataMember(Name = "userStatus", EmitDefaultValue = false)]
+        [DataMember(Name = "userStatus", EmitDefaultValue = true)]
         public int UserStatus { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Whale.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Whale.cs
index e49f7867fdd..b54a43611c4 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Whale.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Whale.cs
@@ -75,7 +75,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Zebra.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
index 34775905ac9..2cc9945a03c 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
@@ -62,8 +62,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Type
         /// </summary>
-        [DataMember(Name = "type", EmitDefaultValue = false)]
-        public TypeEnum? Type { get; set; }
+        [DataMember(Name = "type", EmitDefaultValue = true)]
+        public TypeEnum Type { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Zebra" /> class.
         /// </summary>
@@ -92,7 +92,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
index 8e919c1af84..78d92d5de4a 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
@@ -56,8 +56,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ZeroBasedEnum
         /// </summary>
-        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = false)]
-        public ZeroBasedEnumEnum? ZeroBasedEnum { get; set; }
+        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = true)]
+        public ZeroBasedEnumEnum ZeroBasedEnum { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="ZeroBasedEnumClass" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/ApiResponse.cs b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/ApiResponse.cs
index f419649557f..882db60549c 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/ApiResponse.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/ApiResponse.cs
@@ -48,7 +48,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Code
         /// </summary>
-        [DataMember(Name = "code", EmitDefaultValue = false)]
+        [DataMember(Name = "code", EmitDefaultValue = true)]
         public int Code { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Category.cs b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Category.cs
index 7f5cc435b4d..65518c3ef2a 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Category.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Category.cs
@@ -46,7 +46,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Order.cs b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Order.cs
index 97cc5d2d96e..eaf3bd56121 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Order.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Order.cs
@@ -63,8 +63,8 @@ namespace Org.OpenAPITools.Model
         /// Order Status
         /// </summary>
         /// <value>Order Status</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Order" /> class.
         /// </summary>
@@ -87,19 +87,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets PetId
         /// </summary>
-        [DataMember(Name = "petId", EmitDefaultValue = false)]
+        [DataMember(Name = "petId", EmitDefaultValue = true)]
         public long PetId { get; set; }
 
         /// <summary>
         /// Gets or Sets Quantity
         /// </summary>
-        [DataMember(Name = "quantity", EmitDefaultValue = false)]
+        [DataMember(Name = "quantity", EmitDefaultValue = true)]
         public int Quantity { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Pet.cs b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Pet.cs
index ed1b1913070..f315b0965d5 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Pet.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Pet.cs
@@ -63,9 +63,9 @@ namespace Org.OpenAPITools.Model
         /// pet status in the store
         /// </summary>
         /// <value>pet status in the store</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
+        [DataMember(Name = "status", EmitDefaultValue = true)]
         [Obsolete]
-        public StatusEnum? Status { get; set; }
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Pet" /> class.
         /// </summary>
@@ -103,7 +103,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -118,13 +118,13 @@ namespace Org.OpenAPITools.Model
         /*
         <example>doggie</example>
         */
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
         /// Gets or Sets PhotoUrls
         /// </summary>
-        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = false)]
         public List<string> PhotoUrls { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Tag.cs b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Tag.cs
index 0d025e3446b..8ec0ab161bd 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Tag.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/Tag.cs
@@ -46,7 +46,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/User.cs b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/User.cs
index 4aa50254f0b..e3676608f41 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/User.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Model/User.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -101,7 +101,7 @@ namespace Org.OpenAPITools.Model
         /// User Status
         /// </summary>
         /// <value>User Status</value>
-        [DataMember(Name = "userStatus", EmitDefaultValue = false)]
+        [DataMember(Name = "userStatus", EmitDefaultValue = true)]
         public int UserStatus { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Animal.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Animal.cs
index f6d7f1cf5b6..30c944cff4d 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Animal.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Animal.cs
@@ -65,7 +65,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
index 7dec589c62d..06784267be7 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Code
         /// </summary>
-        [DataMember(Name = "code", EmitDefaultValue = false)]
+        [DataMember(Name = "code", EmitDefaultValue = true)]
         public int Code { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
index 15d96e2ee29..a5938afb489 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
@@ -56,7 +56,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Cultivar
         /// </summary>
-        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = false)]
         public string Cultivar { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Banana.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Banana.cs
index c506c26dbb8..dd2f1b89e91 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Banana.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Banana.cs
@@ -45,7 +45,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets LengthCm
         /// </summary>
-        [DataMember(Name = "lengthCm", EmitDefaultValue = false)]
+        [DataMember(Name = "lengthCm", EmitDefaultValue = true)]
         public decimal LengthCm { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
index bdb25571066..09e9a581bad 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Category.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Category.cs
index b56dfc0c482..1d5de514814 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Category.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Category.cs
@@ -60,13 +60,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
index b5cd8370cb9..663199a8867 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
index f3f19fce57f..7232c6d8fdb 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
index 7a9834a78d1..839aa9328bc 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
@@ -55,8 +55,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustSymbol
         /// </summary>
-        [DataMember(Name = "just_symbol", EmitDefaultValue = false)]
-        public JustSymbolEnum? JustSymbol { get; set; }
+        [DataMember(Name = "just_symbol", EmitDefaultValue = true)]
+        public JustSymbolEnum JustSymbol { get; set; }
         /// <summary>
         /// Defines ArrayEnum
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
index 0851264693b..38dbf965ee1 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
@@ -91,8 +91,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumString
         /// </summary>
-        [DataMember(Name = "enum_string", EmitDefaultValue = false)]
-        public EnumStringEnum? EnumString { get; set; }
+        [DataMember(Name = "enum_string", EmitDefaultValue = true)]
+        public EnumStringEnum EnumString { get; set; }
         /// <summary>
         /// Defines EnumStringRequired
         /// </summary>
@@ -174,8 +174,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumInteger
         /// </summary>
-        [DataMember(Name = "enum_integer", EmitDefaultValue = false)]
-        public EnumIntegerEnum? EnumInteger { get; set; }
+        [DataMember(Name = "enum_integer", EmitDefaultValue = true)]
+        public EnumIntegerEnum EnumInteger { get; set; }
         /// <summary>
         /// Defines EnumIntegerOnly
         /// </summary>
@@ -196,8 +196,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "enum_integer_only", EmitDefaultValue = false)]
-        public EnumIntegerOnlyEnum? EnumIntegerOnly { get; set; }
+        [DataMember(Name = "enum_integer_only", EmitDefaultValue = true)]
+        public EnumIntegerOnlyEnum EnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines EnumNumber
         /// </summary>
@@ -221,32 +221,32 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumNumber
         /// </summary>
-        [DataMember(Name = "enum_number", EmitDefaultValue = false)]
-        public EnumNumberEnum? EnumNumber { get; set; }
+        [DataMember(Name = "enum_number", EmitDefaultValue = true)]
+        public EnumNumberEnum EnumNumber { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnum
         /// </summary>
         [DataMember(Name = "outerEnum", EmitDefaultValue = true)]
-        public OuterEnum? OuterEnum { get; set; }
+        public OuterEnum OuterEnum { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumInteger
         /// </summary>
-        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = false)]
-        public OuterEnumInteger? OuterEnumInteger { get; set; }
+        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = true)]
+        public OuterEnumInteger OuterEnumInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? OuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue OuterEnumDefaultValue { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumIntegerDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumIntegerDefaultValue? OuterEnumIntegerDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumIntegerDefaultValue OuterEnumIntegerDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="EnumTest" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
index 373122a5923..cfb611876ad 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
index 08306695ce0..f7d5c6b450a 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
@@ -99,31 +99,31 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Integer
         /// </summary>
-        [DataMember(Name = "integer", EmitDefaultValue = false)]
+        [DataMember(Name = "integer", EmitDefaultValue = true)]
         public int Integer { get; set; }
 
         /// <summary>
         /// Gets or Sets Int32
         /// </summary>
-        [DataMember(Name = "int32", EmitDefaultValue = false)]
+        [DataMember(Name = "int32", EmitDefaultValue = true)]
         public int Int32 { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedInteger
         /// </summary>
-        [DataMember(Name = "unsigned_integer", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_integer", EmitDefaultValue = true)]
         public uint UnsignedInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64
         /// </summary>
-        [DataMember(Name = "int64", EmitDefaultValue = false)]
+        [DataMember(Name = "int64", EmitDefaultValue = true)]
         public long Int64 { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedLong
         /// </summary>
-        [DataMember(Name = "unsigned_long", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_long", EmitDefaultValue = true)]
         public ulong UnsignedLong { get; set; }
 
         /// <summary>
@@ -135,19 +135,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Float
         /// </summary>
-        [DataMember(Name = "float", EmitDefaultValue = false)]
+        [DataMember(Name = "float", EmitDefaultValue = true)]
         public float Float { get; set; }
 
         /// <summary>
         /// Gets or Sets Double
         /// </summary>
-        [DataMember(Name = "double", EmitDefaultValue = false)]
+        [DataMember(Name = "double", EmitDefaultValue = true)]
         public double Double { get; set; }
 
         /// <summary>
         /// Gets or Sets Decimal
         /// </summary>
-        [DataMember(Name = "decimal", EmitDefaultValue = false)]
+        [DataMember(Name = "decimal", EmitDefaultValue = true)]
         public decimal Decimal { get; set; }
 
         /// <summary>
@@ -159,7 +159,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Byte
         /// </summary>
-        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = false)]
         public byte[] Byte { get; set; }
 
         /// <summary>
@@ -174,7 +174,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>Sun Feb 02 00:00:00 UTC 2020</example>
         */
-        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = false)]
         [JsonConverter(typeof(OpenAPIDateConverter))]
         public DateTime Date { get; set; }
 
@@ -199,7 +199,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Password
         /// </summary>
-        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = false)]
         public string Password { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
index 9d576878b23..7763cc86a01 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
@@ -62,7 +62,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets PetType
         /// </summary>
-        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = false)]
         public string PetType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
index 297e82fd9ba..0594403a58a 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
@@ -61,13 +61,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
index 74b83092923..67b5b17e70f 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", EmitDefaultValue = false)]
+        [DataMember(Name = "name", EmitDefaultValue = true)]
         public int Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Name.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Name.cs
index 4eace322815..6d0af056430 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Name.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Name.cs
@@ -61,7 +61,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SnakeCase
         /// </summary>
-        [DataMember(Name = "snake_case", EmitDefaultValue = false)]
+        [DataMember(Name = "snake_case", EmitDefaultValue = true)]
         public int SnakeCase { get; private set; }
 
         /// <summary>
@@ -81,7 +81,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Var123Number
         /// </summary>
-        [DataMember(Name = "123Number", EmitDefaultValue = false)]
+        [DataMember(Name = "123Number", EmitDefaultValue = true)]
         public int Var123Number { get; private set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
index d99edd0c214..f87a4677aa0 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
@@ -66,7 +66,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets AObjVariableobject
         /// </summary>
-        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = false)]
         public List<Dictionary<string, Object>> AObjVariableobject { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
index cdfc6bae47e..741e520c489 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
@@ -48,7 +48,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustNumber
         /// </summary>
-        [DataMember(Name = "JustNumber", EmitDefaultValue = false)]
+        [DataMember(Name = "JustNumber", EmitDefaultValue = true)]
         public decimal JustNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
index a6fba6e93cc..31ac069c0f0 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
@@ -57,7 +57,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         [Obsolete]
         public decimal Id { get; set; }
 
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Order.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Order.cs
index 8aa03dd2f49..56dc1a0a656 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Order.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Order.cs
@@ -63,8 +63,8 @@ namespace Org.OpenAPITools.Model
         /// Order Status
         /// </summary>
         /// <value>Order Status</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Order" /> class.
         /// </summary>
@@ -88,19 +88,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets PetId
         /// </summary>
-        [DataMember(Name = "petId", EmitDefaultValue = false)]
+        [DataMember(Name = "petId", EmitDefaultValue = true)]
         public long PetId { get; set; }
 
         /// <summary>
         /// Gets or Sets Quantity
         /// </summary>
-        [DataMember(Name = "quantity", EmitDefaultValue = false)]
+        [DataMember(Name = "quantity", EmitDefaultValue = true)]
         public int Quantity { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
index f53ff933dab..9329f734ca9 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets MyNumber
         /// </summary>
-        [DataMember(Name = "my_number", EmitDefaultValue = false)]
+        [DataMember(Name = "my_number", EmitDefaultValue = true)]
         public decimal MyNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Pet.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Pet.cs
index d6cf84c4d73..033d9f92351 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Pet.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Pet.cs
@@ -63,8 +63,8 @@ namespace Org.OpenAPITools.Model
         /// pet status in the store
         /// </summary>
         /// <value>pet status in the store</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Pet" /> class.
         /// </summary>
@@ -106,7 +106,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -121,13 +121,13 @@ namespace Org.OpenAPITools.Model
         /*
         <example>doggie</example>
         */
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
         /// Gets or Sets PhotoUrls
         /// </summary>
-        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = false)]
         public List<string> PhotoUrls { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
index c72cd676bb9..5311acc0977 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
index 596031f228f..26d3c570845 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
@@ -97,7 +97,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableEnumInteger
         /// </summary>
         [DataMember(Name = "notrequired_nullable_enum_integer", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumIntegerEnum? NotrequiredNullableEnumInteger { get; set; }
+        public NotrequiredNullableEnumIntegerEnum NotrequiredNullableEnumInteger { get; set; }
         /// <summary>
         /// Defines NotrequiredNotnullableEnumInteger
         /// </summary>
@@ -118,8 +118,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumInteger
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerEnum? NotrequiredNotnullableEnumInteger { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerEnum NotrequiredNotnullableEnumInteger { get; set; }
         /// <summary>
         /// Defines RequiredNullableEnumIntegerOnly
         /// </summary>
@@ -187,7 +187,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableEnumIntegerOnly
         /// </summary>
         [DataMember(Name = "notrequired_nullable_enum_integer_only", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumIntegerOnlyEnum? NotrequiredNullableEnumIntegerOnly { get; set; }
+        public NotrequiredNullableEnumIntegerOnlyEnum NotrequiredNullableEnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
@@ -208,8 +208,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerOnlyEnum? NotrequiredNotnullableEnumIntegerOnly { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerOnlyEnum NotrequiredNotnullableEnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines RequiredNotnullableEnumString
         /// </summary>
@@ -392,7 +392,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableEnumString
         /// </summary>
         [DataMember(Name = "notrequired_nullable_enum_string", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumStringEnum? NotrequiredNullableEnumString { get; set; }
+        public NotrequiredNullableEnumStringEnum NotrequiredNullableEnumString { get; set; }
         /// <summary>
         /// Defines NotrequiredNotnullableEnumString
         /// </summary>
@@ -452,8 +452,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumString
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumStringEnum? NotrequiredNotnullableEnumString { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumStringEnum NotrequiredNotnullableEnumString { get; set; }
 
         /// <summary>
         /// Gets or Sets RequiredNullableOuterEnumDefaultValue
@@ -471,13 +471,13 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableOuterEnumDefaultValue
         /// </summary>
         [DataMember(Name = "notrequired_nullable_outerEnumDefaultValue", EmitDefaultValue = true)]
-        public OuterEnumDefaultValue? NotrequiredNullableOuterEnumDefaultValue { get; set; }
+        public OuterEnumDefaultValue NotrequiredNullableOuterEnumDefaultValue { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableOuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="RequiredClass" /> class.
         /// </summary>
@@ -648,7 +648,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotRequiredNotnullableintegerProp
         /// </summary>
-        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = false)]
+        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = true)]
         public int NotRequiredNotnullableintegerProp { get; set; }
 
         /// <summary>
@@ -660,7 +660,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableStringProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = false)]
         public string RequiredNotnullableStringProp { get; set; }
 
         /// <summary>
@@ -709,7 +709,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotNullableDateProp
         /// </summary>
-        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = false)]
         [JsonConverter(typeof(OpenAPIDateConverter))]
         public DateTime RequiredNotNullableDateProp { get; set; }
 
@@ -730,7 +730,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableDatetimeProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateTime RequiredNotnullableDatetimeProp { get; set; }
 
         /// <summary>
@@ -766,7 +766,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
-        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = false)]
         public Guid RequiredNotnullableUuid { get; set; }
 
         /// <summary>
@@ -796,7 +796,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableArrayOfString
         /// </summary>
-        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = false)]
         public List<string> RequiredNotnullableArrayOfString { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Return.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Return.cs
index ff745fb8c63..5caf01529f1 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Return.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Return.cs
@@ -45,7 +45,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets VarReturn
         /// </summary>
-        [DataMember(Name = "return", EmitDefaultValue = false)]
+        [DataMember(Name = "return", EmitDefaultValue = true)]
         public int VarReturn { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
index a2f2a020ca0..a9f0145e073 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
index f559e8b8052..141bf5a2beb 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
index c6845db92f2..68c27aea327 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
index eba993bc6df..290f5eca496 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SpecialPropertyName
         /// </summary>
-        [DataMember(Name = "$special[property.name]", EmitDefaultValue = false)]
+        [DataMember(Name = "$special[property.name]", EmitDefaultValue = true)]
         public long SpecialPropertyName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Tag.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Tag.cs
index 662ad9138d5..f93e8b9dad3 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Tag.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Tag.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
index 65b685735f9..90c1a907440 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/User.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/User.cs
index 20b349a6ded..df1f607e5a7 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/User.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/User.cs
@@ -67,7 +67,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -110,7 +110,7 @@ namespace Org.OpenAPITools.Model
         /// User Status
         /// </summary>
         /// <value>User Status</value>
-        [DataMember(Name = "userStatus", EmitDefaultValue = false)]
+        [DataMember(Name = "userStatus", EmitDefaultValue = true)]
         public int UserStatus { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Whale.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Whale.cs
index 85fe2d95bfe..192c7b77c41 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Whale.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Whale.cs
@@ -74,7 +74,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Zebra.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
index 53ea6867b30..9f663bf753e 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
@@ -61,8 +61,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Type
         /// </summary>
-        [DataMember(Name = "type", EmitDefaultValue = false)]
-        public TypeEnum? Type { get; set; }
+        [DataMember(Name = "type", EmitDefaultValue = true)]
+        public TypeEnum Type { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Zebra" /> class.
         /// </summary>
@@ -91,7 +91,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
index 6fa1afb780b..731213824f1 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
@@ -55,8 +55,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ZeroBasedEnum
         /// </summary>
-        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = false)]
-        public ZeroBasedEnumEnum? ZeroBasedEnum { get; set; }
+        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = true)]
+        public ZeroBasedEnumEnum ZeroBasedEnum { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="ZeroBasedEnumClass" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Animal.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Animal.cs
index f6d7f1cf5b6..30c944cff4d 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Animal.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Animal.cs
@@ -65,7 +65,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
index 7dec589c62d..06784267be7 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Code
         /// </summary>
-        [DataMember(Name = "code", EmitDefaultValue = false)]
+        [DataMember(Name = "code", EmitDefaultValue = true)]
         public int Code { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
index 15d96e2ee29..a5938afb489 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
@@ -56,7 +56,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Cultivar
         /// </summary>
-        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = false)]
         public string Cultivar { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Banana.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Banana.cs
index c506c26dbb8..dd2f1b89e91 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Banana.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Banana.cs
@@ -45,7 +45,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets LengthCm
         /// </summary>
-        [DataMember(Name = "lengthCm", EmitDefaultValue = false)]
+        [DataMember(Name = "lengthCm", EmitDefaultValue = true)]
         public decimal LengthCm { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
index bdb25571066..09e9a581bad 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Category.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Category.cs
index b56dfc0c482..1d5de514814 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Category.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Category.cs
@@ -60,13 +60,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
index b5cd8370cb9..663199a8867 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
index f3f19fce57f..7232c6d8fdb 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
index 7a9834a78d1..839aa9328bc 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
@@ -55,8 +55,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustSymbol
         /// </summary>
-        [DataMember(Name = "just_symbol", EmitDefaultValue = false)]
-        public JustSymbolEnum? JustSymbol { get; set; }
+        [DataMember(Name = "just_symbol", EmitDefaultValue = true)]
+        public JustSymbolEnum JustSymbol { get; set; }
         /// <summary>
         /// Defines ArrayEnum
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
index 0851264693b..38dbf965ee1 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
@@ -91,8 +91,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumString
         /// </summary>
-        [DataMember(Name = "enum_string", EmitDefaultValue = false)]
-        public EnumStringEnum? EnumString { get; set; }
+        [DataMember(Name = "enum_string", EmitDefaultValue = true)]
+        public EnumStringEnum EnumString { get; set; }
         /// <summary>
         /// Defines EnumStringRequired
         /// </summary>
@@ -174,8 +174,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumInteger
         /// </summary>
-        [DataMember(Name = "enum_integer", EmitDefaultValue = false)]
-        public EnumIntegerEnum? EnumInteger { get; set; }
+        [DataMember(Name = "enum_integer", EmitDefaultValue = true)]
+        public EnumIntegerEnum EnumInteger { get; set; }
         /// <summary>
         /// Defines EnumIntegerOnly
         /// </summary>
@@ -196,8 +196,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "enum_integer_only", EmitDefaultValue = false)]
-        public EnumIntegerOnlyEnum? EnumIntegerOnly { get; set; }
+        [DataMember(Name = "enum_integer_only", EmitDefaultValue = true)]
+        public EnumIntegerOnlyEnum EnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines EnumNumber
         /// </summary>
@@ -221,32 +221,32 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumNumber
         /// </summary>
-        [DataMember(Name = "enum_number", EmitDefaultValue = false)]
-        public EnumNumberEnum? EnumNumber { get; set; }
+        [DataMember(Name = "enum_number", EmitDefaultValue = true)]
+        public EnumNumberEnum EnumNumber { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnum
         /// </summary>
         [DataMember(Name = "outerEnum", EmitDefaultValue = true)]
-        public OuterEnum? OuterEnum { get; set; }
+        public OuterEnum OuterEnum { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumInteger
         /// </summary>
-        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = false)]
-        public OuterEnumInteger? OuterEnumInteger { get; set; }
+        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = true)]
+        public OuterEnumInteger OuterEnumInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? OuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue OuterEnumDefaultValue { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumIntegerDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumIntegerDefaultValue? OuterEnumIntegerDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumIntegerDefaultValue OuterEnumIntegerDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="EnumTest" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
index 373122a5923..cfb611876ad 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
index 08306695ce0..f7d5c6b450a 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
@@ -99,31 +99,31 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Integer
         /// </summary>
-        [DataMember(Name = "integer", EmitDefaultValue = false)]
+        [DataMember(Name = "integer", EmitDefaultValue = true)]
         public int Integer { get; set; }
 
         /// <summary>
         /// Gets or Sets Int32
         /// </summary>
-        [DataMember(Name = "int32", EmitDefaultValue = false)]
+        [DataMember(Name = "int32", EmitDefaultValue = true)]
         public int Int32 { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedInteger
         /// </summary>
-        [DataMember(Name = "unsigned_integer", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_integer", EmitDefaultValue = true)]
         public uint UnsignedInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64
         /// </summary>
-        [DataMember(Name = "int64", EmitDefaultValue = false)]
+        [DataMember(Name = "int64", EmitDefaultValue = true)]
         public long Int64 { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedLong
         /// </summary>
-        [DataMember(Name = "unsigned_long", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_long", EmitDefaultValue = true)]
         public ulong UnsignedLong { get; set; }
 
         /// <summary>
@@ -135,19 +135,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Float
         /// </summary>
-        [DataMember(Name = "float", EmitDefaultValue = false)]
+        [DataMember(Name = "float", EmitDefaultValue = true)]
         public float Float { get; set; }
 
         /// <summary>
         /// Gets or Sets Double
         /// </summary>
-        [DataMember(Name = "double", EmitDefaultValue = false)]
+        [DataMember(Name = "double", EmitDefaultValue = true)]
         public double Double { get; set; }
 
         /// <summary>
         /// Gets or Sets Decimal
         /// </summary>
-        [DataMember(Name = "decimal", EmitDefaultValue = false)]
+        [DataMember(Name = "decimal", EmitDefaultValue = true)]
         public decimal Decimal { get; set; }
 
         /// <summary>
@@ -159,7 +159,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Byte
         /// </summary>
-        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = false)]
         public byte[] Byte { get; set; }
 
         /// <summary>
@@ -174,7 +174,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>Sun Feb 02 00:00:00 UTC 2020</example>
         */
-        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = false)]
         [JsonConverter(typeof(OpenAPIDateConverter))]
         public DateTime Date { get; set; }
 
@@ -199,7 +199,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Password
         /// </summary>
-        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = false)]
         public string Password { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
index 9d576878b23..7763cc86a01 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
@@ -62,7 +62,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets PetType
         /// </summary>
-        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = false)]
         public string PetType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
index 297e82fd9ba..0594403a58a 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
@@ -61,13 +61,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
index 74b83092923..67b5b17e70f 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", EmitDefaultValue = false)]
+        [DataMember(Name = "name", EmitDefaultValue = true)]
         public int Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Name.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Name.cs
index 4eace322815..6d0af056430 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Name.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Name.cs
@@ -61,7 +61,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SnakeCase
         /// </summary>
-        [DataMember(Name = "snake_case", EmitDefaultValue = false)]
+        [DataMember(Name = "snake_case", EmitDefaultValue = true)]
         public int SnakeCase { get; private set; }
 
         /// <summary>
@@ -81,7 +81,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Var123Number
         /// </summary>
-        [DataMember(Name = "123Number", EmitDefaultValue = false)]
+        [DataMember(Name = "123Number", EmitDefaultValue = true)]
         public int Var123Number { get; private set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
index d99edd0c214..f87a4677aa0 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
@@ -66,7 +66,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets AObjVariableobject
         /// </summary>
-        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = false)]
         public List<Dictionary<string, Object>> AObjVariableobject { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
index cdfc6bae47e..741e520c489 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
@@ -48,7 +48,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustNumber
         /// </summary>
-        [DataMember(Name = "JustNumber", EmitDefaultValue = false)]
+        [DataMember(Name = "JustNumber", EmitDefaultValue = true)]
         public decimal JustNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
index a6fba6e93cc..31ac069c0f0 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
@@ -57,7 +57,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         [Obsolete]
         public decimal Id { get; set; }
 
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Order.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Order.cs
index 8aa03dd2f49..56dc1a0a656 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Order.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Order.cs
@@ -63,8 +63,8 @@ namespace Org.OpenAPITools.Model
         /// Order Status
         /// </summary>
         /// <value>Order Status</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Order" /> class.
         /// </summary>
@@ -88,19 +88,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets PetId
         /// </summary>
-        [DataMember(Name = "petId", EmitDefaultValue = false)]
+        [DataMember(Name = "petId", EmitDefaultValue = true)]
         public long PetId { get; set; }
 
         /// <summary>
         /// Gets or Sets Quantity
         /// </summary>
-        [DataMember(Name = "quantity", EmitDefaultValue = false)]
+        [DataMember(Name = "quantity", EmitDefaultValue = true)]
         public int Quantity { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
index f53ff933dab..9329f734ca9 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets MyNumber
         /// </summary>
-        [DataMember(Name = "my_number", EmitDefaultValue = false)]
+        [DataMember(Name = "my_number", EmitDefaultValue = true)]
         public decimal MyNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Pet.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Pet.cs
index d6cf84c4d73..033d9f92351 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Pet.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Pet.cs
@@ -63,8 +63,8 @@ namespace Org.OpenAPITools.Model
         /// pet status in the store
         /// </summary>
         /// <value>pet status in the store</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Pet" /> class.
         /// </summary>
@@ -106,7 +106,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -121,13 +121,13 @@ namespace Org.OpenAPITools.Model
         /*
         <example>doggie</example>
         */
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
         /// Gets or Sets PhotoUrls
         /// </summary>
-        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = false)]
         public List<string> PhotoUrls { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
index c72cd676bb9..5311acc0977 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
index 596031f228f..26d3c570845 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
@@ -97,7 +97,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableEnumInteger
         /// </summary>
         [DataMember(Name = "notrequired_nullable_enum_integer", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumIntegerEnum? NotrequiredNullableEnumInteger { get; set; }
+        public NotrequiredNullableEnumIntegerEnum NotrequiredNullableEnumInteger { get; set; }
         /// <summary>
         /// Defines NotrequiredNotnullableEnumInteger
         /// </summary>
@@ -118,8 +118,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumInteger
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerEnum? NotrequiredNotnullableEnumInteger { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerEnum NotrequiredNotnullableEnumInteger { get; set; }
         /// <summary>
         /// Defines RequiredNullableEnumIntegerOnly
         /// </summary>
@@ -187,7 +187,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableEnumIntegerOnly
         /// </summary>
         [DataMember(Name = "notrequired_nullable_enum_integer_only", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumIntegerOnlyEnum? NotrequiredNullableEnumIntegerOnly { get; set; }
+        public NotrequiredNullableEnumIntegerOnlyEnum NotrequiredNullableEnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
@@ -208,8 +208,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerOnlyEnum? NotrequiredNotnullableEnumIntegerOnly { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerOnlyEnum NotrequiredNotnullableEnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines RequiredNotnullableEnumString
         /// </summary>
@@ -392,7 +392,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableEnumString
         /// </summary>
         [DataMember(Name = "notrequired_nullable_enum_string", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumStringEnum? NotrequiredNullableEnumString { get; set; }
+        public NotrequiredNullableEnumStringEnum NotrequiredNullableEnumString { get; set; }
         /// <summary>
         /// Defines NotrequiredNotnullableEnumString
         /// </summary>
@@ -452,8 +452,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumString
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumStringEnum? NotrequiredNotnullableEnumString { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumStringEnum NotrequiredNotnullableEnumString { get; set; }
 
         /// <summary>
         /// Gets or Sets RequiredNullableOuterEnumDefaultValue
@@ -471,13 +471,13 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableOuterEnumDefaultValue
         /// </summary>
         [DataMember(Name = "notrequired_nullable_outerEnumDefaultValue", EmitDefaultValue = true)]
-        public OuterEnumDefaultValue? NotrequiredNullableOuterEnumDefaultValue { get; set; }
+        public OuterEnumDefaultValue NotrequiredNullableOuterEnumDefaultValue { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableOuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="RequiredClass" /> class.
         /// </summary>
@@ -648,7 +648,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotRequiredNotnullableintegerProp
         /// </summary>
-        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = false)]
+        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = true)]
         public int NotRequiredNotnullableintegerProp { get; set; }
 
         /// <summary>
@@ -660,7 +660,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableStringProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = false)]
         public string RequiredNotnullableStringProp { get; set; }
 
         /// <summary>
@@ -709,7 +709,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotNullableDateProp
         /// </summary>
-        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = false)]
         [JsonConverter(typeof(OpenAPIDateConverter))]
         public DateTime RequiredNotNullableDateProp { get; set; }
 
@@ -730,7 +730,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableDatetimeProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateTime RequiredNotnullableDatetimeProp { get; set; }
 
         /// <summary>
@@ -766,7 +766,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
-        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = false)]
         public Guid RequiredNotnullableUuid { get; set; }
 
         /// <summary>
@@ -796,7 +796,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableArrayOfString
         /// </summary>
-        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = false)]
         public List<string> RequiredNotnullableArrayOfString { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Return.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Return.cs
index ff745fb8c63..5caf01529f1 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Return.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Return.cs
@@ -45,7 +45,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets VarReturn
         /// </summary>
-        [DataMember(Name = "return", EmitDefaultValue = false)]
+        [DataMember(Name = "return", EmitDefaultValue = true)]
         public int VarReturn { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
index a2f2a020ca0..a9f0145e073 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
index f559e8b8052..141bf5a2beb 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
index c6845db92f2..68c27aea327 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
index eba993bc6df..290f5eca496 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SpecialPropertyName
         /// </summary>
-        [DataMember(Name = "$special[property.name]", EmitDefaultValue = false)]
+        [DataMember(Name = "$special[property.name]", EmitDefaultValue = true)]
         public long SpecialPropertyName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Tag.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Tag.cs
index 662ad9138d5..f93e8b9dad3 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Tag.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Tag.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
index 65b685735f9..90c1a907440 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/User.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/User.cs
index 20b349a6ded..df1f607e5a7 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/User.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/User.cs
@@ -67,7 +67,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -110,7 +110,7 @@ namespace Org.OpenAPITools.Model
         /// User Status
         /// </summary>
         /// <value>User Status</value>
-        [DataMember(Name = "userStatus", EmitDefaultValue = false)]
+        [DataMember(Name = "userStatus", EmitDefaultValue = true)]
         public int UserStatus { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Whale.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Whale.cs
index 85fe2d95bfe..192c7b77c41 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Whale.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Whale.cs
@@ -74,7 +74,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Zebra.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
index 53ea6867b30..9f663bf753e 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
@@ -61,8 +61,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Type
         /// </summary>
-        [DataMember(Name = "type", EmitDefaultValue = false)]
-        public TypeEnum? Type { get; set; }
+        [DataMember(Name = "type", EmitDefaultValue = true)]
+        public TypeEnum Type { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Zebra" /> class.
         /// </summary>
@@ -91,7 +91,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
index 6fa1afb780b..731213824f1 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
@@ -55,8 +55,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ZeroBasedEnum
         /// </summary>
-        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = false)]
-        public ZeroBasedEnumEnum? ZeroBasedEnum { get; set; }
+        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = true)]
+        public ZeroBasedEnumEnum ZeroBasedEnum { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="ZeroBasedEnumClass" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs
index 99aff9d787c..2329d45991b 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs
@@ -72,7 +72,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets Anytype1
         /// </summary>
         [DataMember(Name = "anytype_1", EmitDefaultValue = true)]
-        public Object Anytype1 { get; set; }
+        public Object? Anytype1 { get; set; }
 
         /// <summary>
         /// Gets or Sets MapWithUndeclaredPropertiesAnytype1
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Animal.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Animal.cs
index f6d7f1cf5b6..30c944cff4d 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Animal.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Animal.cs
@@ -65,7 +65,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ApiResponse.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ApiResponse.cs
index 7dec589c62d..06784267be7 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ApiResponse.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ApiResponse.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Code
         /// </summary>
-        [DataMember(Name = "code", EmitDefaultValue = false)]
+        [DataMember(Name = "code", EmitDefaultValue = true)]
         public int Code { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/AppleReq.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/AppleReq.cs
index 15d96e2ee29..a5938afb489 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/AppleReq.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/AppleReq.cs
@@ -56,7 +56,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Cultivar
         /// </summary>
-        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = false)]
         public string Cultivar { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Banana.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Banana.cs
index c506c26dbb8..dd2f1b89e91 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Banana.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Banana.cs
@@ -45,7 +45,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets LengthCm
         /// </summary>
-        [DataMember(Name = "lengthCm", EmitDefaultValue = false)]
+        [DataMember(Name = "lengthCm", EmitDefaultValue = true)]
         public decimal LengthCm { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/BasquePig.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/BasquePig.cs
index bdb25571066..09e9a581bad 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/BasquePig.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/BasquePig.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Category.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Category.cs
index b56dfc0c482..1d5de514814 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Category.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Category.cs
@@ -60,13 +60,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
index b5cd8370cb9..663199a8867 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/DanishPig.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/DanishPig.cs
index f3f19fce57f..7232c6d8fdb 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/DanishPig.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/DanishPig.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Drawing.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Drawing.cs
index f9918311cf5..ed5b044f252 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Drawing.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Drawing.cs
@@ -58,13 +58,13 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets ShapeOrNull
         /// </summary>
         [DataMember(Name = "shapeOrNull", EmitDefaultValue = true)]
-        public ShapeOrNull ShapeOrNull { get; set; }
+        public ShapeOrNull? ShapeOrNull { get; set; }
 
         /// <summary>
         /// Gets or Sets NullableShape
         /// </summary>
         [DataMember(Name = "nullableShape", EmitDefaultValue = true)]
-        public NullableShape NullableShape { get; set; }
+        public NullableShape? NullableShape { get; set; }
 
         /// <summary>
         /// Gets or Sets Shapes
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/EnumArrays.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/EnumArrays.cs
index 7a9834a78d1..839aa9328bc 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/EnumArrays.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/EnumArrays.cs
@@ -55,8 +55,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustSymbol
         /// </summary>
-        [DataMember(Name = "just_symbol", EmitDefaultValue = false)]
-        public JustSymbolEnum? JustSymbol { get; set; }
+        [DataMember(Name = "just_symbol", EmitDefaultValue = true)]
+        public JustSymbolEnum JustSymbol { get; set; }
         /// <summary>
         /// Defines ArrayEnum
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/EnumTest.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/EnumTest.cs
index 0851264693b..72b557ecb57 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/EnumTest.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/EnumTest.cs
@@ -91,8 +91,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumString
         /// </summary>
-        [DataMember(Name = "enum_string", EmitDefaultValue = false)]
-        public EnumStringEnum? EnumString { get; set; }
+        [DataMember(Name = "enum_string", EmitDefaultValue = true)]
+        public EnumStringEnum EnumString { get; set; }
         /// <summary>
         /// Defines EnumStringRequired
         /// </summary>
@@ -174,8 +174,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumInteger
         /// </summary>
-        [DataMember(Name = "enum_integer", EmitDefaultValue = false)]
-        public EnumIntegerEnum? EnumInteger { get; set; }
+        [DataMember(Name = "enum_integer", EmitDefaultValue = true)]
+        public EnumIntegerEnum EnumInteger { get; set; }
         /// <summary>
         /// Defines EnumIntegerOnly
         /// </summary>
@@ -196,8 +196,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "enum_integer_only", EmitDefaultValue = false)]
-        public EnumIntegerOnlyEnum? EnumIntegerOnly { get; set; }
+        [DataMember(Name = "enum_integer_only", EmitDefaultValue = true)]
+        public EnumIntegerOnlyEnum EnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines EnumNumber
         /// </summary>
@@ -221,8 +221,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumNumber
         /// </summary>
-        [DataMember(Name = "enum_number", EmitDefaultValue = false)]
-        public EnumNumberEnum? EnumNumber { get; set; }
+        [DataMember(Name = "enum_number", EmitDefaultValue = true)]
+        public EnumNumberEnum EnumNumber { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnum
@@ -233,20 +233,20 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets OuterEnumInteger
         /// </summary>
-        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = false)]
-        public OuterEnumInteger? OuterEnumInteger { get; set; }
+        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = true)]
+        public OuterEnumInteger OuterEnumInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? OuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue OuterEnumDefaultValue { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumIntegerDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumIntegerDefaultValue? OuterEnumIntegerDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumIntegerDefaultValue OuterEnumIntegerDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="EnumTest" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/EquilateralTriangle.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
index 373122a5923..cfb611876ad 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/FormatTest.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/FormatTest.cs
index f036de12837..d3a9fff394d 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/FormatTest.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/FormatTest.cs
@@ -99,31 +99,31 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Integer
         /// </summary>
-        [DataMember(Name = "integer", EmitDefaultValue = false)]
+        [DataMember(Name = "integer", EmitDefaultValue = true)]
         public int Integer { get; set; }
 
         /// <summary>
         /// Gets or Sets Int32
         /// </summary>
-        [DataMember(Name = "int32", EmitDefaultValue = false)]
+        [DataMember(Name = "int32", EmitDefaultValue = true)]
         public int Int32 { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedInteger
         /// </summary>
-        [DataMember(Name = "unsigned_integer", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_integer", EmitDefaultValue = true)]
         public uint UnsignedInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64
         /// </summary>
-        [DataMember(Name = "int64", EmitDefaultValue = false)]
+        [DataMember(Name = "int64", EmitDefaultValue = true)]
         public long Int64 { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedLong
         /// </summary>
-        [DataMember(Name = "unsigned_long", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_long", EmitDefaultValue = true)]
         public ulong UnsignedLong { get; set; }
 
         /// <summary>
@@ -135,19 +135,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Float
         /// </summary>
-        [DataMember(Name = "float", EmitDefaultValue = false)]
+        [DataMember(Name = "float", EmitDefaultValue = true)]
         public float Float { get; set; }
 
         /// <summary>
         /// Gets or Sets Double
         /// </summary>
-        [DataMember(Name = "double", EmitDefaultValue = false)]
+        [DataMember(Name = "double", EmitDefaultValue = true)]
         public double Double { get; set; }
 
         /// <summary>
         /// Gets or Sets Decimal
         /// </summary>
-        [DataMember(Name = "decimal", EmitDefaultValue = false)]
+        [DataMember(Name = "decimal", EmitDefaultValue = true)]
         public decimal Decimal { get; set; }
 
         /// <summary>
@@ -159,7 +159,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Byte
         /// </summary>
-        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = false)]
         public byte[] Byte { get; set; }
 
         /// <summary>
@@ -174,7 +174,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>Sun Feb 02 00:00:00 UTC 2020</example>
         */
-        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = false)]
         public DateOnly Date { get; set; }
 
         /// <summary>
@@ -198,7 +198,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Password
         /// </summary>
-        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = false)]
         public string Password { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/GrandparentAnimal.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
index 9d576878b23..7763cc86a01 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
@@ -62,7 +62,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets PetType
         /// </summary>
-        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = false)]
         public string PetType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/HealthCheckResult.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/HealthCheckResult.cs
index abb6777f0a7..bdc29cc87af 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/HealthCheckResult.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/HealthCheckResult.cs
@@ -46,7 +46,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NullableMessage
         /// </summary>
         [DataMember(Name = "NullableMessage", EmitDefaultValue = true)]
-        public string NullableMessage { get; set; }
+        public string? NullableMessage { get; set; }
 
         /// <summary>
         /// Gets or Sets additional properties
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
index 297e82fd9ba..0594403a58a 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
@@ -61,13 +61,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Model200Response.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Model200Response.cs
index 74b83092923..67b5b17e70f 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Model200Response.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Model200Response.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", EmitDefaultValue = false)]
+        [DataMember(Name = "name", EmitDefaultValue = true)]
         public int Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Name.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Name.cs
index 4eace322815..6d0af056430 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Name.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Name.cs
@@ -61,7 +61,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SnakeCase
         /// </summary>
-        [DataMember(Name = "snake_case", EmitDefaultValue = false)]
+        [DataMember(Name = "snake_case", EmitDefaultValue = true)]
         public int SnakeCase { get; private set; }
 
         /// <summary>
@@ -81,7 +81,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Var123Number
         /// </summary>
-        [DataMember(Name = "123Number", EmitDefaultValue = false)]
+        [DataMember(Name = "123Number", EmitDefaultValue = true)]
         public int Var123Number { get; private set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
index d99edd0c214..f87a4677aa0 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
@@ -66,7 +66,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets AObjVariableobject
         /// </summary>
-        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = false)]
         public List<Dictionary<string, Object>> AObjVariableobject { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NullableClass.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NullableClass.cs
index 7a69c3751d0..a310b9a45bf 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NullableClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NullableClass.cs
@@ -68,49 +68,49 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets IntegerProp
         /// </summary>
         [DataMember(Name = "integer_prop", EmitDefaultValue = true)]
-        public int? IntegerProp { get; set; }
+        public int?? IntegerProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NumberProp
         /// </summary>
         [DataMember(Name = "number_prop", EmitDefaultValue = true)]
-        public decimal? NumberProp { get; set; }
+        public decimal?? NumberProp { get; set; }
 
         /// <summary>
         /// Gets or Sets BooleanProp
         /// </summary>
         [DataMember(Name = "boolean_prop", EmitDefaultValue = true)]
-        public bool? BooleanProp { get; set; }
+        public bool?? BooleanProp { get; set; }
 
         /// <summary>
         /// Gets or Sets StringProp
         /// </summary>
         [DataMember(Name = "string_prop", EmitDefaultValue = true)]
-        public string StringProp { get; set; }
+        public string? StringProp { get; set; }
 
         /// <summary>
         /// 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
         /// </summary>
         [DataMember(Name = "datetime_prop", EmitDefaultValue = true)]
-        public DateTime? DatetimeProp { get; set; }
+        public DateTime?? DatetimeProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayNullableProp
         /// </summary>
         [DataMember(Name = "array_nullable_prop", EmitDefaultValue = true)]
-        public List<Object> ArrayNullableProp { get; set; }
+        public List<Object>? ArrayNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayAndItemsNullableProp
         /// </summary>
         [DataMember(Name = "array_and_items_nullable_prop", EmitDefaultValue = true)]
-        public List<Object> ArrayAndItemsNullableProp { get; set; }
+        public List<Object>? ArrayAndItemsNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayItemsNullable
@@ -122,13 +122,13 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets ObjectNullableProp
         /// </summary>
         [DataMember(Name = "object_nullable_prop", EmitDefaultValue = true)]
-        public Dictionary<string, Object> ObjectNullableProp { get; set; }
+        public Dictionary<string, Object>? ObjectNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ObjectAndItemsNullableProp
         /// </summary>
         [DataMember(Name = "object_and_items_nullable_prop", EmitDefaultValue = true)]
-        public Dictionary<string, Object> ObjectAndItemsNullableProp { get; set; }
+        public Dictionary<string, Object>? ObjectAndItemsNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ObjectItemsNullable
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NullableGuidClass.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NullableGuidClass.cs
index 36bc2546dee..dd21804363a 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NullableGuidClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NullableGuidClass.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
         [DataMember(Name = "uuid", EmitDefaultValue = true)]
-        public Guid? Uuid { get; set; }
+        public Guid?? Uuid { get; set; }
 
         /// <summary>
         /// Gets or Sets additional properties
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NumberOnly.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NumberOnly.cs
index cdfc6bae47e..741e520c489 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NumberOnly.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/NumberOnly.cs
@@ -48,7 +48,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustNumber
         /// </summary>
-        [DataMember(Name = "JustNumber", EmitDefaultValue = false)]
+        [DataMember(Name = "JustNumber", EmitDefaultValue = true)]
         public decimal JustNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
index a6fba6e93cc..31ac069c0f0 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
@@ -57,7 +57,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         [Obsolete]
         public decimal Id { get; set; }
 
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Order.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Order.cs
index 6b8d5b26836..b3f952a3d6f 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Order.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Order.cs
@@ -63,8 +63,8 @@ namespace Org.OpenAPITools.Model
         /// Order Status
         /// </summary>
         /// <value>Order Status</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Order" /> class.
         /// </summary>
@@ -88,19 +88,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets PetId
         /// </summary>
-        [DataMember(Name = "petId", EmitDefaultValue = false)]
+        [DataMember(Name = "petId", EmitDefaultValue = true)]
         public long PetId { get; set; }
 
         /// <summary>
         /// Gets or Sets Quantity
         /// </summary>
-        [DataMember(Name = "quantity", EmitDefaultValue = false)]
+        [DataMember(Name = "quantity", EmitDefaultValue = true)]
         public int Quantity { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/OuterComposite.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/OuterComposite.cs
index f53ff933dab..9329f734ca9 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/OuterComposite.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/OuterComposite.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets MyNumber
         /// </summary>
-        [DataMember(Name = "my_number", EmitDefaultValue = false)]
+        [DataMember(Name = "my_number", EmitDefaultValue = true)]
         public decimal MyNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Pet.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Pet.cs
index d6cf84c4d73..033d9f92351 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Pet.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Pet.cs
@@ -63,8 +63,8 @@ namespace Org.OpenAPITools.Model
         /// pet status in the store
         /// </summary>
         /// <value>pet status in the store</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Pet" /> class.
         /// </summary>
@@ -106,7 +106,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -121,13 +121,13 @@ namespace Org.OpenAPITools.Model
         /*
         <example>doggie</example>
         */
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
         /// Gets or Sets PhotoUrls
         /// </summary>
-        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = false)]
         public List<string> PhotoUrls { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
index c72cd676bb9..5311acc0977 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/RequiredClass.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/RequiredClass.cs
index ea6ec3cd4ce..e199c8c4ef4 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/RequiredClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/RequiredClass.cs
@@ -118,8 +118,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumInteger
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerEnum? NotrequiredNotnullableEnumInteger { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerEnum NotrequiredNotnullableEnumInteger { get; set; }
         /// <summary>
         /// Defines RequiredNullableEnumIntegerOnly
         /// </summary>
@@ -208,8 +208,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerOnlyEnum? NotrequiredNotnullableEnumIntegerOnly { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerOnlyEnum NotrequiredNotnullableEnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines RequiredNotnullableEnumString
         /// </summary>
@@ -452,8 +452,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumString
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumStringEnum? NotrequiredNotnullableEnumString { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumStringEnum NotrequiredNotnullableEnumString { get; set; }
 
         /// <summary>
         /// Gets or Sets RequiredNullableOuterEnumDefaultValue
@@ -476,8 +476,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableOuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="RequiredClass" /> class.
         /// </summary>
@@ -643,12 +643,12 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotRequiredNullableIntegerProp
         /// </summary>
         [DataMember(Name = "not_required_nullable_integer_prop", EmitDefaultValue = true)]
-        public int? NotRequiredNullableIntegerProp { get; set; }
+        public int?? NotRequiredNullableIntegerProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotRequiredNotnullableintegerProp
         /// </summary>
-        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = false)]
+        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = true)]
         public int NotRequiredNotnullableintegerProp { get; set; }
 
         /// <summary>
@@ -660,14 +660,14 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableStringProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = false)]
         public string RequiredNotnullableStringProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNullableStringProp
         /// </summary>
         [DataMember(Name = "notrequired_nullable_string_prop", EmitDefaultValue = true)]
-        public string NotrequiredNullableStringProp { get; set; }
+        public string? NotrequiredNullableStringProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableStringProp
@@ -691,7 +691,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableBooleanProp
         /// </summary>
         [DataMember(Name = "notrequired_nullable_boolean_prop", EmitDefaultValue = true)]
-        public bool? NotrequiredNullableBooleanProp { get; set; }
+        public bool?? NotrequiredNullableBooleanProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableBooleanProp
@@ -708,14 +708,14 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotNullableDateProp
         /// </summary>
-        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateOnly RequiredNotNullableDateProp { get; set; }
 
         /// <summary>
         /// 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
@@ -726,7 +726,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableDatetimeProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateTime RequiredNotnullableDatetimeProp { get; set; }
 
         /// <summary>
@@ -739,7 +739,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableDatetimeProp
         /// </summary>
         [DataMember(Name = "notrequired_nullable_datetime_prop", EmitDefaultValue = true)]
-        public DateTime? NotrequiredNullableDatetimeProp { get; set; }
+        public DateTime?? NotrequiredNullableDatetimeProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableDatetimeProp
@@ -762,7 +762,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
-        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = false)]
         public Guid RequiredNotnullableUuid { get; set; }
 
         /// <summary>
@@ -772,7 +772,7 @@ namespace Org.OpenAPITools.Model
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
         [DataMember(Name = "notrequired_nullable_uuid", EmitDefaultValue = true)]
-        public Guid? NotrequiredNullableUuid { get; set; }
+        public Guid?? NotrequiredNullableUuid { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableUuid
@@ -792,14 +792,14 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableArrayOfString
         /// </summary>
-        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = false)]
         public List<string> RequiredNotnullableArrayOfString { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNullableArrayOfString
         /// </summary>
         [DataMember(Name = "notrequired_nullable_array_of_string", EmitDefaultValue = true)]
-        public List<string> NotrequiredNullableArrayOfString { get; set; }
+        public List<string>? NotrequiredNullableArrayOfString { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableArrayOfString
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Return.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Return.cs
index ff745fb8c63..5caf01529f1 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Return.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Return.cs
@@ -45,7 +45,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets VarReturn
         /// </summary>
-        [DataMember(Name = "return", EmitDefaultValue = false)]
+        [DataMember(Name = "return", EmitDefaultValue = true)]
         public int VarReturn { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ScaleneTriangle.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
index a2f2a020ca0..a9f0145e073 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ShapeInterface.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ShapeInterface.cs
index f559e8b8052..141bf5a2beb 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ShapeInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ShapeInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
index c6845db92f2..68c27aea327 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/SpecialModelName.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/SpecialModelName.cs
index eba993bc6df..290f5eca496 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/SpecialModelName.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/SpecialModelName.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SpecialPropertyName
         /// </summary>
-        [DataMember(Name = "$special[property.name]", EmitDefaultValue = false)]
+        [DataMember(Name = "$special[property.name]", EmitDefaultValue = true)]
         public long SpecialPropertyName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Tag.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Tag.cs
index 662ad9138d5..f93e8b9dad3 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Tag.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Tag.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/TriangleInterface.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/TriangleInterface.cs
index 65b685735f9..90c1a907440 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/TriangleInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/TriangleInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/User.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/User.cs
index 20b349a6ded..f1285e6e975 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/User.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/User.cs
@@ -67,7 +67,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -110,7 +110,7 @@ namespace Org.OpenAPITools.Model
         /// User Status
         /// </summary>
         /// <value>User Status</value>
-        [DataMember(Name = "userStatus", EmitDefaultValue = false)]
+        [DataMember(Name = "userStatus", EmitDefaultValue = true)]
         public int UserStatus { get; set; }
 
         /// <summary>
@@ -125,21 +125,21 @@ namespace Org.OpenAPITools.Model
         /// </summary>
         /// <value>test code generation for nullable objects. Value must be a map of strings to values or the &#39;null&#39; value.</value>
         [DataMember(Name = "objectWithNoDeclaredPropsNullable", EmitDefaultValue = true)]
-        public Object ObjectWithNoDeclaredPropsNullable { get; set; }
+        public Object? ObjectWithNoDeclaredPropsNullable { get; set; }
 
         /// <summary>
         /// test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. See https://github.com/OAI/OpenAPI-Specification/issues/1389
         /// </summary>
         /// <value>test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. See https://github.com/OAI/OpenAPI-Specification/issues/1389</value>
         [DataMember(Name = "anyTypeProp", EmitDefaultValue = true)]
-        public Object AnyTypeProp { get; set; }
+        public Object? AnyTypeProp { get; set; }
 
         /// <summary>
         /// test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. The &#39;nullable&#39; attribute does not change the allowed values.
         /// </summary>
         /// <value>test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. The &#39;nullable&#39; attribute does not change the allowed values.</value>
         [DataMember(Name = "anyTypePropNullable", EmitDefaultValue = true)]
-        public Object AnyTypePropNullable { get; set; }
+        public Object? AnyTypePropNullable { get; set; }
 
         /// <summary>
         /// Gets or Sets additional properties
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Whale.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Whale.cs
index 85fe2d95bfe..192c7b77c41 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Whale.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Whale.cs
@@ -74,7 +74,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Zebra.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Zebra.cs
index 53ea6867b30..9f663bf753e 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Zebra.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/Zebra.cs
@@ -61,8 +61,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Type
         /// </summary>
-        [DataMember(Name = "type", EmitDefaultValue = false)]
-        public TypeEnum? Type { get; set; }
+        [DataMember(Name = "type", EmitDefaultValue = true)]
+        public TypeEnum Type { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Zebra" /> class.
         /// </summary>
@@ -91,7 +91,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
index 6fa1afb780b..731213824f1 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
@@ -55,8 +55,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ZeroBasedEnum
         /// </summary>
-        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = false)]
-        public ZeroBasedEnumEnum? ZeroBasedEnum { get; set; }
+        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = true)]
+        public ZeroBasedEnumEnum ZeroBasedEnum { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="ZeroBasedEnumClass" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs
index b5bfc54646f..957a4ad2c59 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs
@@ -71,7 +71,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets Anytype1
         /// </summary>
         [DataMember(Name = "anytype_1", EmitDefaultValue = true)]
-        public Object Anytype1 { get; set; }
+        public Object? Anytype1 { get; set; }
 
         /// <summary>
         /// Gets or Sets MapWithUndeclaredPropertiesAnytype1
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Animal.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Animal.cs
index 5bebc284924..7fc3a53be2f 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Animal.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Animal.cs
@@ -61,7 +61,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
index ed83e9c9079..79f7046d43f 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
@@ -48,7 +48,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Code
         /// </summary>
-        [DataMember(Name = "code", EmitDefaultValue = false)]
+        [DataMember(Name = "code", EmitDefaultValue = true)]
         public int Code { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
index 15d96e2ee29..a5938afb489 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
@@ -56,7 +56,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Cultivar
         /// </summary>
-        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = false)]
         public string Cultivar { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Banana.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Banana.cs
index 7100a90faf0..334ce2d6559 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Banana.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Banana.cs
@@ -44,7 +44,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets LengthCm
         /// </summary>
-        [DataMember(Name = "lengthCm", EmitDefaultValue = false)]
+        [DataMember(Name = "lengthCm", EmitDefaultValue = true)]
         public decimal LengthCm { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
index 9c7a372b8ba..a0b0cd87470 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
@@ -54,7 +54,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Category.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Category.cs
index 4e9591df4cc..081eeb19a16 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Category.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Category.cs
@@ -56,13 +56,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
index 2feaeae90e1..59db22569d9 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
@@ -61,13 +61,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs
index 96416b82ded..cea7494d6a0 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs
@@ -76,7 +76,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets CopyActivitytt
         /// </summary>
-        [DataMember(Name = "copyActivitytt", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "copyActivitytt", IsRequired = true, EmitDefaultValue = false)]
         public string CopyActivitytt { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
index ca40481c94f..8d328f4c4f4 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
@@ -54,7 +54,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Drawing.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Drawing.cs
index f9918311cf5..ed5b044f252 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Drawing.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Drawing.cs
@@ -58,13 +58,13 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets ShapeOrNull
         /// </summary>
         [DataMember(Name = "shapeOrNull", EmitDefaultValue = true)]
-        public ShapeOrNull ShapeOrNull { get; set; }
+        public ShapeOrNull? ShapeOrNull { get; set; }
 
         /// <summary>
         /// Gets or Sets NullableShape
         /// </summary>
         [DataMember(Name = "nullableShape", EmitDefaultValue = true)]
-        public NullableShape NullableShape { get; set; }
+        public NullableShape? NullableShape { get; set; }
 
         /// <summary>
         /// Gets or Sets Shapes
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs
index d657ab5587c..51d0254d853 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs
@@ -57,7 +57,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Schema
         /// </summary>
-        [DataMember(Name = "$schema", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "$schema", IsRequired = true, EmitDefaultValue = false)]
         public string Schema { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
index 7dd8b1c9e01..6d10541cfef 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
@@ -55,8 +55,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustSymbol
         /// </summary>
-        [DataMember(Name = "just_symbol", EmitDefaultValue = false)]
-        public JustSymbolEnum? JustSymbol { get; set; }
+        [DataMember(Name = "just_symbol", EmitDefaultValue = true)]
+        public JustSymbolEnum JustSymbol { get; set; }
         /// <summary>
         /// Defines ArrayEnum
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
index 5d6b305bb33..af8646ac99b 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
@@ -91,8 +91,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumString
         /// </summary>
-        [DataMember(Name = "enum_string", EmitDefaultValue = false)]
-        public EnumStringEnum? EnumString { get; set; }
+        [DataMember(Name = "enum_string", EmitDefaultValue = true)]
+        public EnumStringEnum EnumString { get; set; }
         /// <summary>
         /// Defines EnumStringRequired
         /// </summary>
@@ -174,8 +174,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumInteger
         /// </summary>
-        [DataMember(Name = "enum_integer", EmitDefaultValue = false)]
-        public EnumIntegerEnum? EnumInteger { get; set; }
+        [DataMember(Name = "enum_integer", EmitDefaultValue = true)]
+        public EnumIntegerEnum EnumInteger { get; set; }
         /// <summary>
         /// Defines EnumIntegerOnly
         /// </summary>
@@ -196,8 +196,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "enum_integer_only", EmitDefaultValue = false)]
-        public EnumIntegerOnlyEnum? EnumIntegerOnly { get; set; }
+        [DataMember(Name = "enum_integer_only", EmitDefaultValue = true)]
+        public EnumIntegerOnlyEnum EnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines EnumNumber
         /// </summary>
@@ -221,8 +221,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumNumber
         /// </summary>
-        [DataMember(Name = "enum_number", EmitDefaultValue = false)]
-        public EnumNumberEnum? EnumNumber { get; set; }
+        [DataMember(Name = "enum_number", EmitDefaultValue = true)]
+        public EnumNumberEnum EnumNumber { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnum
@@ -233,20 +233,20 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets OuterEnumInteger
         /// </summary>
-        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = false)]
-        public OuterEnumInteger? OuterEnumInteger { get; set; }
+        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = true)]
+        public OuterEnumInteger OuterEnumInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? OuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue OuterEnumDefaultValue { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumIntegerDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumIntegerDefaultValue? OuterEnumIntegerDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumIntegerDefaultValue OuterEnumIntegerDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="EnumTest" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
index 8d90f3fd594..0d6ebb5c684 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
@@ -61,13 +61,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
index 408766a19d1..2dd0cda95af 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
@@ -109,61 +109,61 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Integer
         /// </summary>
-        [DataMember(Name = "integer", EmitDefaultValue = false)]
+        [DataMember(Name = "integer", EmitDefaultValue = true)]
         public int Integer { get; set; }
 
         /// <summary>
         /// Gets or Sets Int32
         /// </summary>
-        [DataMember(Name = "int32", EmitDefaultValue = false)]
+        [DataMember(Name = "int32", EmitDefaultValue = true)]
         public int Int32 { get; set; }
 
         /// <summary>
         /// Gets or Sets Int32Range
         /// </summary>
-        [DataMember(Name = "int32Range", EmitDefaultValue = false)]
+        [DataMember(Name = "int32Range", EmitDefaultValue = true)]
         public int Int32Range { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64Positive
         /// </summary>
-        [DataMember(Name = "int64Positive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64Positive", EmitDefaultValue = true)]
         public long Int64Positive { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64Negative
         /// </summary>
-        [DataMember(Name = "int64Negative", EmitDefaultValue = false)]
+        [DataMember(Name = "int64Negative", EmitDefaultValue = true)]
         public long Int64Negative { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64PositiveExclusive
         /// </summary>
-        [DataMember(Name = "int64PositiveExclusive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64PositiveExclusive", EmitDefaultValue = true)]
         public long Int64PositiveExclusive { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64NegativeExclusive
         /// </summary>
-        [DataMember(Name = "int64NegativeExclusive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64NegativeExclusive", EmitDefaultValue = true)]
         public long Int64NegativeExclusive { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedInteger
         /// </summary>
-        [DataMember(Name = "unsigned_integer", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_integer", EmitDefaultValue = true)]
         public uint UnsignedInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64
         /// </summary>
-        [DataMember(Name = "int64", EmitDefaultValue = false)]
+        [DataMember(Name = "int64", EmitDefaultValue = true)]
         public long Int64 { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedLong
         /// </summary>
-        [DataMember(Name = "unsigned_long", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_long", EmitDefaultValue = true)]
         public ulong UnsignedLong { get; set; }
 
         /// <summary>
@@ -175,19 +175,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Float
         /// </summary>
-        [DataMember(Name = "float", EmitDefaultValue = false)]
+        [DataMember(Name = "float", EmitDefaultValue = true)]
         public float Float { get; set; }
 
         /// <summary>
         /// Gets or Sets Double
         /// </summary>
-        [DataMember(Name = "double", EmitDefaultValue = false)]
+        [DataMember(Name = "double", EmitDefaultValue = true)]
         public double Double { get; set; }
 
         /// <summary>
         /// Gets or Sets Decimal
         /// </summary>
-        [DataMember(Name = "decimal", EmitDefaultValue = false)]
+        [DataMember(Name = "decimal", EmitDefaultValue = true)]
         public decimal Decimal { get; set; }
 
         /// <summary>
@@ -199,7 +199,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Byte
         /// </summary>
-        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = false)]
         public byte[] Byte { get; set; }
 
         /// <summary>
@@ -214,7 +214,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>Sun Feb 02 00:00:00 UTC 2020</example>
         */
-        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = false)]
         public DateOnly Date { get; set; }
 
         /// <summary>
@@ -238,7 +238,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Password
         /// </summary>
-        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = false)]
         public string Password { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
index 54208034faf..1d5410bf3bd 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets PetType
         /// </summary>
-        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = false)]
         public string PetType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/HealthCheckResult.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/HealthCheckResult.cs
index 79bcfc38ed5..12e596f2353 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/HealthCheckResult.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/HealthCheckResult.cs
@@ -45,7 +45,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NullableMessage
         /// </summary>
         [DataMember(Name = "NullableMessage", EmitDefaultValue = true)]
-        public string NullableMessage { get; set; }
+        public string? NullableMessage { get; set; }
 
         /// <summary>
         /// Returns the string presentation of the object
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
index 297e82fd9ba..0594403a58a 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
@@ -61,13 +61,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
index 40318b19ff8..f6dfcc4ff01 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
@@ -46,7 +46,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", EmitDefaultValue = false)]
+        [DataMember(Name = "name", EmitDefaultValue = true)]
         public int Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Name.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Name.cs
index 8c7eab2b0f9..d5d31e6b38f 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Name.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Name.cs
@@ -57,7 +57,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SnakeCase
         /// </summary>
-        [DataMember(Name = "snake_case", EmitDefaultValue = false)]
+        [DataMember(Name = "snake_case", EmitDefaultValue = true)]
         public int SnakeCase { get; private set; }
 
         /// <summary>
@@ -77,7 +77,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Var123Number
         /// </summary>
-        [DataMember(Name = "123Number", EmitDefaultValue = false)]
+        [DataMember(Name = "123Number", EmitDefaultValue = true)]
         public int Var123Number { get; private set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
index 3ffceba8816..a3efa84eae8 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
@@ -62,7 +62,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets AObjVariableobject
         /// </summary>
-        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = false)]
         public List<Dictionary<string, Object>> AObjVariableobject { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs
index 7a69c3751d0..a310b9a45bf 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs
@@ -68,49 +68,49 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets IntegerProp
         /// </summary>
         [DataMember(Name = "integer_prop", EmitDefaultValue = true)]
-        public int? IntegerProp { get; set; }
+        public int?? IntegerProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NumberProp
         /// </summary>
         [DataMember(Name = "number_prop", EmitDefaultValue = true)]
-        public decimal? NumberProp { get; set; }
+        public decimal?? NumberProp { get; set; }
 
         /// <summary>
         /// Gets or Sets BooleanProp
         /// </summary>
         [DataMember(Name = "boolean_prop", EmitDefaultValue = true)]
-        public bool? BooleanProp { get; set; }
+        public bool?? BooleanProp { get; set; }
 
         /// <summary>
         /// Gets or Sets StringProp
         /// </summary>
         [DataMember(Name = "string_prop", EmitDefaultValue = true)]
-        public string StringProp { get; set; }
+        public string? StringProp { get; set; }
 
         /// <summary>
         /// 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
         /// </summary>
         [DataMember(Name = "datetime_prop", EmitDefaultValue = true)]
-        public DateTime? DatetimeProp { get; set; }
+        public DateTime?? DatetimeProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayNullableProp
         /// </summary>
         [DataMember(Name = "array_nullable_prop", EmitDefaultValue = true)]
-        public List<Object> ArrayNullableProp { get; set; }
+        public List<Object>? ArrayNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayAndItemsNullableProp
         /// </summary>
         [DataMember(Name = "array_and_items_nullable_prop", EmitDefaultValue = true)]
-        public List<Object> ArrayAndItemsNullableProp { get; set; }
+        public List<Object>? ArrayAndItemsNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayItemsNullable
@@ -122,13 +122,13 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets ObjectNullableProp
         /// </summary>
         [DataMember(Name = "object_nullable_prop", EmitDefaultValue = true)]
-        public Dictionary<string, Object> ObjectNullableProp { get; set; }
+        public Dictionary<string, Object>? ObjectNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ObjectAndItemsNullableProp
         /// </summary>
         [DataMember(Name = "object_and_items_nullable_prop", EmitDefaultValue = true)]
-        public Dictionary<string, Object> ObjectAndItemsNullableProp { get; set; }
+        public Dictionary<string, Object>? ObjectAndItemsNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ObjectItemsNullable
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NullableGuidClass.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NullableGuidClass.cs
index a03996310c5..a0dc49a2dab 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NullableGuidClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NullableGuidClass.cs
@@ -48,7 +48,7 @@ namespace Org.OpenAPITools.Model
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
         [DataMember(Name = "uuid", EmitDefaultValue = true)]
-        public Guid? Uuid { get; set; }
+        public Guid?? Uuid { get; set; }
 
         /// <summary>
         /// Returns the string presentation of the object
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
index 0c5015ded6e..7c335b5ec89 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustNumber
         /// </summary>
-        [DataMember(Name = "JustNumber", EmitDefaultValue = false)]
+        [DataMember(Name = "JustNumber", EmitDefaultValue = true)]
         public decimal JustNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
index 5d1b92de8fe..7fab4b43e4c 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
@@ -56,7 +56,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         [Obsolete]
         public decimal Id { get; set; }
 
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Order.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Order.cs
index ae9d7efd80b..1c722fb0023 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Order.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Order.cs
@@ -63,8 +63,8 @@ namespace Org.OpenAPITools.Model
         /// Order Status
         /// </summary>
         /// <value>Order Status</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Order" /> class.
         /// </summary>
@@ -87,19 +87,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets PetId
         /// </summary>
-        [DataMember(Name = "petId", EmitDefaultValue = false)]
+        [DataMember(Name = "petId", EmitDefaultValue = true)]
         public long PetId { get; set; }
 
         /// <summary>
         /// Gets or Sets Quantity
         /// </summary>
-        [DataMember(Name = "quantity", EmitDefaultValue = false)]
+        [DataMember(Name = "quantity", EmitDefaultValue = true)]
         public int Quantity { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
index 3512652479c..f149a52fa9f 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
@@ -48,7 +48,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets MyNumber
         /// </summary>
-        [DataMember(Name = "my_number", EmitDefaultValue = false)]
+        [DataMember(Name = "my_number", EmitDefaultValue = true)]
         public decimal MyNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Pet.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Pet.cs
index aaac5180f51..c5875645adf 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Pet.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Pet.cs
@@ -63,8 +63,8 @@ namespace Org.OpenAPITools.Model
         /// pet status in the store
         /// </summary>
         /// <value>pet status in the store</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Pet" /> class.
         /// </summary>
@@ -102,7 +102,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -117,13 +117,13 @@ namespace Org.OpenAPITools.Model
         /*
         <example>doggie</example>
         */
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
         /// Gets or Sets PhotoUrls
         /// </summary>
-        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = false)]
         public List<string> PhotoUrls { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
index 14728fe2a11..aff1b67cca1 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
@@ -54,7 +54,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
index 403137a821e..182b1c4dfdf 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
@@ -118,8 +118,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumInteger
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerEnum? NotrequiredNotnullableEnumInteger { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerEnum NotrequiredNotnullableEnumInteger { get; set; }
         /// <summary>
         /// Defines RequiredNullableEnumIntegerOnly
         /// </summary>
@@ -208,8 +208,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerOnlyEnum? NotrequiredNotnullableEnumIntegerOnly { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerOnlyEnum NotrequiredNotnullableEnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines RequiredNotnullableEnumString
         /// </summary>
@@ -452,8 +452,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumString
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumStringEnum? NotrequiredNotnullableEnumString { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumStringEnum NotrequiredNotnullableEnumString { get; set; }
 
         /// <summary>
         /// Gets or Sets RequiredNullableOuterEnumDefaultValue
@@ -476,8 +476,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableOuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="RequiredClass" /> class.
         /// </summary>
@@ -639,12 +639,12 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotRequiredNullableIntegerProp
         /// </summary>
         [DataMember(Name = "not_required_nullable_integer_prop", EmitDefaultValue = true)]
-        public int? NotRequiredNullableIntegerProp { get; set; }
+        public int?? NotRequiredNullableIntegerProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotRequiredNotnullableintegerProp
         /// </summary>
-        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = false)]
+        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = true)]
         public int NotRequiredNotnullableintegerProp { get; set; }
 
         /// <summary>
@@ -656,14 +656,14 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableStringProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = false)]
         public string RequiredNotnullableStringProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNullableStringProp
         /// </summary>
         [DataMember(Name = "notrequired_nullable_string_prop", EmitDefaultValue = true)]
-        public string NotrequiredNullableStringProp { get; set; }
+        public string? NotrequiredNullableStringProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableStringProp
@@ -687,7 +687,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableBooleanProp
         /// </summary>
         [DataMember(Name = "notrequired_nullable_boolean_prop", EmitDefaultValue = true)]
-        public bool? NotrequiredNullableBooleanProp { get; set; }
+        public bool?? NotrequiredNullableBooleanProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableBooleanProp
@@ -704,14 +704,14 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotNullableDateProp
         /// </summary>
-        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateOnly RequiredNotNullableDateProp { get; set; }
 
         /// <summary>
         /// 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
@@ -722,7 +722,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableDatetimeProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateTime RequiredNotnullableDatetimeProp { get; set; }
 
         /// <summary>
@@ -735,7 +735,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableDatetimeProp
         /// </summary>
         [DataMember(Name = "notrequired_nullable_datetime_prop", EmitDefaultValue = true)]
-        public DateTime? NotrequiredNullableDatetimeProp { get; set; }
+        public DateTime?? NotrequiredNullableDatetimeProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableDatetimeProp
@@ -758,7 +758,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
-        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = false)]
         public Guid RequiredNotnullableUuid { get; set; }
 
         /// <summary>
@@ -768,7 +768,7 @@ namespace Org.OpenAPITools.Model
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
         [DataMember(Name = "notrequired_nullable_uuid", EmitDefaultValue = true)]
-        public Guid? NotrequiredNullableUuid { get; set; }
+        public Guid?? NotrequiredNullableUuid { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableUuid
@@ -788,14 +788,14 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableArrayOfString
         /// </summary>
-        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = false)]
         public List<string> RequiredNotnullableArrayOfString { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNullableArrayOfString
         /// </summary>
         [DataMember(Name = "notrequired_nullable_array_of_string", EmitDefaultValue = true)]
-        public List<string> NotrequiredNullableArrayOfString { get; set; }
+        public List<string>? NotrequiredNullableArrayOfString { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableArrayOfString
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Return.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Return.cs
index aeb4413b4b3..ed77f232e8f 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Return.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Return.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets VarReturn
         /// </summary>
-        [DataMember(Name = "return", EmitDefaultValue = false)]
+        [DataMember(Name = "return", EmitDefaultValue = true)]
         public int VarReturn { get; set; }
 
         /// <summary>
         /// Gets or Sets Lock
         /// </summary>
-        [DataMember(Name = "lock", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "lock", IsRequired = true, EmitDefaultValue = false)]
         public string Lock { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
index 2594a92e33a..05c8ddb5072 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
@@ -61,13 +61,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
index 67cd6f93c11..74cb255029c 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
@@ -54,7 +54,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
index 3ee8519261a..663a6355d57 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
@@ -61,13 +61,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
index 94d720398f8..9af99645a4c 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
@@ -46,7 +46,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SpecialPropertyName
         /// </summary>
-        [DataMember(Name = "$special[property.name]", EmitDefaultValue = false)]
+        [DataMember(Name = "$special[property.name]", EmitDefaultValue = true)]
         public long SpecialPropertyName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Tag.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Tag.cs
index 57eaeca6d84..401cfd13d6d 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Tag.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Tag.cs
@@ -46,7 +46,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
index 0324ee2cb42..57c28d30532 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
@@ -54,7 +54,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/User.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/User.cs
index 9a38afa6252..77c19cbd7b9 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/User.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/User.cs
@@ -66,7 +66,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -109,7 +109,7 @@ namespace Org.OpenAPITools.Model
         /// User Status
         /// </summary>
         /// <value>User Status</value>
-        [DataMember(Name = "userStatus", EmitDefaultValue = false)]
+        [DataMember(Name = "userStatus", EmitDefaultValue = true)]
         public int UserStatus { get; set; }
 
         /// <summary>
@@ -124,21 +124,21 @@ namespace Org.OpenAPITools.Model
         /// </summary>
         /// <value>test code generation for nullable objects. Value must be a map of strings to values or the &#39;null&#39; value.</value>
         [DataMember(Name = "objectWithNoDeclaredPropsNullable", EmitDefaultValue = true)]
-        public Object ObjectWithNoDeclaredPropsNullable { get; set; }
+        public Object? ObjectWithNoDeclaredPropsNullable { get; set; }
 
         /// <summary>
         /// test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. See https://github.com/OAI/OpenAPI-Specification/issues/1389
         /// </summary>
         /// <value>test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. See https://github.com/OAI/OpenAPI-Specification/issues/1389</value>
         [DataMember(Name = "anyTypeProp", EmitDefaultValue = true)]
-        public Object AnyTypeProp { get; set; }
+        public Object? AnyTypeProp { get; set; }
 
         /// <summary>
         /// test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. The &#39;nullable&#39; attribute does not change the allowed values.
         /// </summary>
         /// <value>test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. The &#39;nullable&#39; attribute does not change the allowed values.</value>
         [DataMember(Name = "anyTypePropNullable", EmitDefaultValue = true)]
-        public Object AnyTypePropNullable { get; set; }
+        public Object? AnyTypePropNullable { get; set; }
 
         /// <summary>
         /// Returns the string presentation of the object
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Whale.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Whale.cs
index b5c2dc8e894..f9a06fa65f1 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Whale.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Whale.cs
@@ -70,7 +70,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Zebra.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
index 53ea6867b30..9f663bf753e 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
@@ -61,8 +61,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Type
         /// </summary>
-        [DataMember(Name = "type", EmitDefaultValue = false)]
-        public TypeEnum? Type { get; set; }
+        [DataMember(Name = "type", EmitDefaultValue = true)]
+        public TypeEnum Type { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Zebra" /> class.
         /// </summary>
@@ -91,7 +91,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
index 690fb260db2..23a0b1f5c42 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
@@ -55,8 +55,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ZeroBasedEnum
         /// </summary>
-        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = false)]
-        public ZeroBasedEnumEnum? ZeroBasedEnum { get; set; }
+        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = true)]
+        public ZeroBasedEnumEnum ZeroBasedEnum { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="ZeroBasedEnumClass" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs
index 99aff9d787c..2329d45991b 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs
@@ -72,7 +72,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets Anytype1
         /// </summary>
         [DataMember(Name = "anytype_1", EmitDefaultValue = true)]
-        public Object Anytype1 { get; set; }
+        public Object? Anytype1 { get; set; }
 
         /// <summary>
         /// Gets or Sets MapWithUndeclaredPropertiesAnytype1
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Animal.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Animal.cs
index f6d7f1cf5b6..30c944cff4d 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Animal.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Animal.cs
@@ -65,7 +65,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ApiResponse.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ApiResponse.cs
index 7dec589c62d..06784267be7 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ApiResponse.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ApiResponse.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Code
         /// </summary>
-        [DataMember(Name = "code", EmitDefaultValue = false)]
+        [DataMember(Name = "code", EmitDefaultValue = true)]
         public int Code { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/AppleReq.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/AppleReq.cs
index 15d96e2ee29..a5938afb489 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/AppleReq.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/AppleReq.cs
@@ -56,7 +56,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Cultivar
         /// </summary>
-        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = false)]
         public string Cultivar { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Banana.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Banana.cs
index c506c26dbb8..dd2f1b89e91 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Banana.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Banana.cs
@@ -45,7 +45,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets LengthCm
         /// </summary>
-        [DataMember(Name = "lengthCm", EmitDefaultValue = false)]
+        [DataMember(Name = "lengthCm", EmitDefaultValue = true)]
         public decimal LengthCm { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/BasquePig.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/BasquePig.cs
index bdb25571066..09e9a581bad 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/BasquePig.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/BasquePig.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Category.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Category.cs
index b56dfc0c482..1d5de514814 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Category.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Category.cs
@@ -60,13 +60,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
index b5cd8370cb9..663199a8867 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/DanishPig.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/DanishPig.cs
index f3f19fce57f..7232c6d8fdb 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/DanishPig.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/DanishPig.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Drawing.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Drawing.cs
index f9918311cf5..ed5b044f252 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Drawing.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Drawing.cs
@@ -58,13 +58,13 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets ShapeOrNull
         /// </summary>
         [DataMember(Name = "shapeOrNull", EmitDefaultValue = true)]
-        public ShapeOrNull ShapeOrNull { get; set; }
+        public ShapeOrNull? ShapeOrNull { get; set; }
 
         /// <summary>
         /// Gets or Sets NullableShape
         /// </summary>
         [DataMember(Name = "nullableShape", EmitDefaultValue = true)]
-        public NullableShape NullableShape { get; set; }
+        public NullableShape? NullableShape { get; set; }
 
         /// <summary>
         /// Gets or Sets Shapes
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/EnumArrays.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/EnumArrays.cs
index 7a9834a78d1..839aa9328bc 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/EnumArrays.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/EnumArrays.cs
@@ -55,8 +55,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustSymbol
         /// </summary>
-        [DataMember(Name = "just_symbol", EmitDefaultValue = false)]
-        public JustSymbolEnum? JustSymbol { get; set; }
+        [DataMember(Name = "just_symbol", EmitDefaultValue = true)]
+        public JustSymbolEnum JustSymbol { get; set; }
         /// <summary>
         /// Defines ArrayEnum
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/EnumTest.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/EnumTest.cs
index 0851264693b..72b557ecb57 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/EnumTest.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/EnumTest.cs
@@ -91,8 +91,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumString
         /// </summary>
-        [DataMember(Name = "enum_string", EmitDefaultValue = false)]
-        public EnumStringEnum? EnumString { get; set; }
+        [DataMember(Name = "enum_string", EmitDefaultValue = true)]
+        public EnumStringEnum EnumString { get; set; }
         /// <summary>
         /// Defines EnumStringRequired
         /// </summary>
@@ -174,8 +174,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumInteger
         /// </summary>
-        [DataMember(Name = "enum_integer", EmitDefaultValue = false)]
-        public EnumIntegerEnum? EnumInteger { get; set; }
+        [DataMember(Name = "enum_integer", EmitDefaultValue = true)]
+        public EnumIntegerEnum EnumInteger { get; set; }
         /// <summary>
         /// Defines EnumIntegerOnly
         /// </summary>
@@ -196,8 +196,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "enum_integer_only", EmitDefaultValue = false)]
-        public EnumIntegerOnlyEnum? EnumIntegerOnly { get; set; }
+        [DataMember(Name = "enum_integer_only", EmitDefaultValue = true)]
+        public EnumIntegerOnlyEnum EnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines EnumNumber
         /// </summary>
@@ -221,8 +221,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumNumber
         /// </summary>
-        [DataMember(Name = "enum_number", EmitDefaultValue = false)]
-        public EnumNumberEnum? EnumNumber { get; set; }
+        [DataMember(Name = "enum_number", EmitDefaultValue = true)]
+        public EnumNumberEnum EnumNumber { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnum
@@ -233,20 +233,20 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets OuterEnumInteger
         /// </summary>
-        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = false)]
-        public OuterEnumInteger? OuterEnumInteger { get; set; }
+        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = true)]
+        public OuterEnumInteger OuterEnumInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? OuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue OuterEnumDefaultValue { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumIntegerDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumIntegerDefaultValue? OuterEnumIntegerDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumIntegerDefaultValue OuterEnumIntegerDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="EnumTest" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/EquilateralTriangle.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
index 373122a5923..cfb611876ad 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/FormatTest.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/FormatTest.cs
index f036de12837..d3a9fff394d 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/FormatTest.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/FormatTest.cs
@@ -99,31 +99,31 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Integer
         /// </summary>
-        [DataMember(Name = "integer", EmitDefaultValue = false)]
+        [DataMember(Name = "integer", EmitDefaultValue = true)]
         public int Integer { get; set; }
 
         /// <summary>
         /// Gets or Sets Int32
         /// </summary>
-        [DataMember(Name = "int32", EmitDefaultValue = false)]
+        [DataMember(Name = "int32", EmitDefaultValue = true)]
         public int Int32 { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedInteger
         /// </summary>
-        [DataMember(Name = "unsigned_integer", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_integer", EmitDefaultValue = true)]
         public uint UnsignedInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64
         /// </summary>
-        [DataMember(Name = "int64", EmitDefaultValue = false)]
+        [DataMember(Name = "int64", EmitDefaultValue = true)]
         public long Int64 { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedLong
         /// </summary>
-        [DataMember(Name = "unsigned_long", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_long", EmitDefaultValue = true)]
         public ulong UnsignedLong { get; set; }
 
         /// <summary>
@@ -135,19 +135,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Float
         /// </summary>
-        [DataMember(Name = "float", EmitDefaultValue = false)]
+        [DataMember(Name = "float", EmitDefaultValue = true)]
         public float Float { get; set; }
 
         /// <summary>
         /// Gets or Sets Double
         /// </summary>
-        [DataMember(Name = "double", EmitDefaultValue = false)]
+        [DataMember(Name = "double", EmitDefaultValue = true)]
         public double Double { get; set; }
 
         /// <summary>
         /// Gets or Sets Decimal
         /// </summary>
-        [DataMember(Name = "decimal", EmitDefaultValue = false)]
+        [DataMember(Name = "decimal", EmitDefaultValue = true)]
         public decimal Decimal { get; set; }
 
         /// <summary>
@@ -159,7 +159,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Byte
         /// </summary>
-        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = false)]
         public byte[] Byte { get; set; }
 
         /// <summary>
@@ -174,7 +174,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>Sun Feb 02 00:00:00 UTC 2020</example>
         */
-        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = false)]
         public DateOnly Date { get; set; }
 
         /// <summary>
@@ -198,7 +198,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Password
         /// </summary>
-        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = false)]
         public string Password { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/GrandparentAnimal.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
index 9d576878b23..7763cc86a01 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
@@ -62,7 +62,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets PetType
         /// </summary>
-        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = false)]
         public string PetType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/HealthCheckResult.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/HealthCheckResult.cs
index abb6777f0a7..bdc29cc87af 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/HealthCheckResult.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/HealthCheckResult.cs
@@ -46,7 +46,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NullableMessage
         /// </summary>
         [DataMember(Name = "NullableMessage", EmitDefaultValue = true)]
-        public string NullableMessage { get; set; }
+        public string? NullableMessage { get; set; }
 
         /// <summary>
         /// Gets or Sets additional properties
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
index 297e82fd9ba..0594403a58a 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
@@ -61,13 +61,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Model200Response.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Model200Response.cs
index 74b83092923..67b5b17e70f 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Model200Response.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Model200Response.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", EmitDefaultValue = false)]
+        [DataMember(Name = "name", EmitDefaultValue = true)]
         public int Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Name.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Name.cs
index 4eace322815..6d0af056430 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Name.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Name.cs
@@ -61,7 +61,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SnakeCase
         /// </summary>
-        [DataMember(Name = "snake_case", EmitDefaultValue = false)]
+        [DataMember(Name = "snake_case", EmitDefaultValue = true)]
         public int SnakeCase { get; private set; }
 
         /// <summary>
@@ -81,7 +81,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Var123Number
         /// </summary>
-        [DataMember(Name = "123Number", EmitDefaultValue = false)]
+        [DataMember(Name = "123Number", EmitDefaultValue = true)]
         public int Var123Number { get; private set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
index d99edd0c214..f87a4677aa0 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
@@ -66,7 +66,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets AObjVariableobject
         /// </summary>
-        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = false)]
         public List<Dictionary<string, Object>> AObjVariableobject { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NullableClass.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NullableClass.cs
index 7a69c3751d0..a310b9a45bf 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NullableClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NullableClass.cs
@@ -68,49 +68,49 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets IntegerProp
         /// </summary>
         [DataMember(Name = "integer_prop", EmitDefaultValue = true)]
-        public int? IntegerProp { get; set; }
+        public int?? IntegerProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NumberProp
         /// </summary>
         [DataMember(Name = "number_prop", EmitDefaultValue = true)]
-        public decimal? NumberProp { get; set; }
+        public decimal?? NumberProp { get; set; }
 
         /// <summary>
         /// Gets or Sets BooleanProp
         /// </summary>
         [DataMember(Name = "boolean_prop", EmitDefaultValue = true)]
-        public bool? BooleanProp { get; set; }
+        public bool?? BooleanProp { get; set; }
 
         /// <summary>
         /// Gets or Sets StringProp
         /// </summary>
         [DataMember(Name = "string_prop", EmitDefaultValue = true)]
-        public string StringProp { get; set; }
+        public string? StringProp { get; set; }
 
         /// <summary>
         /// 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
         /// </summary>
         [DataMember(Name = "datetime_prop", EmitDefaultValue = true)]
-        public DateTime? DatetimeProp { get; set; }
+        public DateTime?? DatetimeProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayNullableProp
         /// </summary>
         [DataMember(Name = "array_nullable_prop", EmitDefaultValue = true)]
-        public List<Object> ArrayNullableProp { get; set; }
+        public List<Object>? ArrayNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayAndItemsNullableProp
         /// </summary>
         [DataMember(Name = "array_and_items_nullable_prop", EmitDefaultValue = true)]
-        public List<Object> ArrayAndItemsNullableProp { get; set; }
+        public List<Object>? ArrayAndItemsNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayItemsNullable
@@ -122,13 +122,13 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets ObjectNullableProp
         /// </summary>
         [DataMember(Name = "object_nullable_prop", EmitDefaultValue = true)]
-        public Dictionary<string, Object> ObjectNullableProp { get; set; }
+        public Dictionary<string, Object>? ObjectNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ObjectAndItemsNullableProp
         /// </summary>
         [DataMember(Name = "object_and_items_nullable_prop", EmitDefaultValue = true)]
-        public Dictionary<string, Object> ObjectAndItemsNullableProp { get; set; }
+        public Dictionary<string, Object>? ObjectAndItemsNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ObjectItemsNullable
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NullableGuidClass.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NullableGuidClass.cs
index 36bc2546dee..dd21804363a 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NullableGuidClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NullableGuidClass.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
         [DataMember(Name = "uuid", EmitDefaultValue = true)]
-        public Guid? Uuid { get; set; }
+        public Guid?? Uuid { get; set; }
 
         /// <summary>
         /// Gets or Sets additional properties
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NumberOnly.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NumberOnly.cs
index cdfc6bae47e..741e520c489 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NumberOnly.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/NumberOnly.cs
@@ -48,7 +48,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustNumber
         /// </summary>
-        [DataMember(Name = "JustNumber", EmitDefaultValue = false)]
+        [DataMember(Name = "JustNumber", EmitDefaultValue = true)]
         public decimal JustNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
index a6fba6e93cc..31ac069c0f0 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
@@ -57,7 +57,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         [Obsolete]
         public decimal Id { get; set; }
 
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Order.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Order.cs
index 6b8d5b26836..b3f952a3d6f 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Order.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Order.cs
@@ -63,8 +63,8 @@ namespace Org.OpenAPITools.Model
         /// Order Status
         /// </summary>
         /// <value>Order Status</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Order" /> class.
         /// </summary>
@@ -88,19 +88,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets PetId
         /// </summary>
-        [DataMember(Name = "petId", EmitDefaultValue = false)]
+        [DataMember(Name = "petId", EmitDefaultValue = true)]
         public long PetId { get; set; }
 
         /// <summary>
         /// Gets or Sets Quantity
         /// </summary>
-        [DataMember(Name = "quantity", EmitDefaultValue = false)]
+        [DataMember(Name = "quantity", EmitDefaultValue = true)]
         public int Quantity { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/OuterComposite.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/OuterComposite.cs
index f53ff933dab..9329f734ca9 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/OuterComposite.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/OuterComposite.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets MyNumber
         /// </summary>
-        [DataMember(Name = "my_number", EmitDefaultValue = false)]
+        [DataMember(Name = "my_number", EmitDefaultValue = true)]
         public decimal MyNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Pet.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Pet.cs
index d6cf84c4d73..033d9f92351 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Pet.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Pet.cs
@@ -63,8 +63,8 @@ namespace Org.OpenAPITools.Model
         /// pet status in the store
         /// </summary>
         /// <value>pet status in the store</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Pet" /> class.
         /// </summary>
@@ -106,7 +106,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -121,13 +121,13 @@ namespace Org.OpenAPITools.Model
         /*
         <example>doggie</example>
         */
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
         /// Gets or Sets PhotoUrls
         /// </summary>
-        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = false)]
         public List<string> PhotoUrls { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
index c72cd676bb9..5311acc0977 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/RequiredClass.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/RequiredClass.cs
index ea6ec3cd4ce..e199c8c4ef4 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/RequiredClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/RequiredClass.cs
@@ -118,8 +118,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumInteger
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerEnum? NotrequiredNotnullableEnumInteger { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerEnum NotrequiredNotnullableEnumInteger { get; set; }
         /// <summary>
         /// Defines RequiredNullableEnumIntegerOnly
         /// </summary>
@@ -208,8 +208,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerOnlyEnum? NotrequiredNotnullableEnumIntegerOnly { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerOnlyEnum NotrequiredNotnullableEnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines RequiredNotnullableEnumString
         /// </summary>
@@ -452,8 +452,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumString
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumStringEnum? NotrequiredNotnullableEnumString { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumStringEnum NotrequiredNotnullableEnumString { get; set; }
 
         /// <summary>
         /// Gets or Sets RequiredNullableOuterEnumDefaultValue
@@ -476,8 +476,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableOuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="RequiredClass" /> class.
         /// </summary>
@@ -643,12 +643,12 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotRequiredNullableIntegerProp
         /// </summary>
         [DataMember(Name = "not_required_nullable_integer_prop", EmitDefaultValue = true)]
-        public int? NotRequiredNullableIntegerProp { get; set; }
+        public int?? NotRequiredNullableIntegerProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotRequiredNotnullableintegerProp
         /// </summary>
-        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = false)]
+        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = true)]
         public int NotRequiredNotnullableintegerProp { get; set; }
 
         /// <summary>
@@ -660,14 +660,14 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableStringProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = false)]
         public string RequiredNotnullableStringProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNullableStringProp
         /// </summary>
         [DataMember(Name = "notrequired_nullable_string_prop", EmitDefaultValue = true)]
-        public string NotrequiredNullableStringProp { get; set; }
+        public string? NotrequiredNullableStringProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableStringProp
@@ -691,7 +691,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableBooleanProp
         /// </summary>
         [DataMember(Name = "notrequired_nullable_boolean_prop", EmitDefaultValue = true)]
-        public bool? NotrequiredNullableBooleanProp { get; set; }
+        public bool?? NotrequiredNullableBooleanProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableBooleanProp
@@ -708,14 +708,14 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotNullableDateProp
         /// </summary>
-        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateOnly RequiredNotNullableDateProp { get; set; }
 
         /// <summary>
         /// 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
@@ -726,7 +726,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableDatetimeProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateTime RequiredNotnullableDatetimeProp { get; set; }
 
         /// <summary>
@@ -739,7 +739,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableDatetimeProp
         /// </summary>
         [DataMember(Name = "notrequired_nullable_datetime_prop", EmitDefaultValue = true)]
-        public DateTime? NotrequiredNullableDatetimeProp { get; set; }
+        public DateTime?? NotrequiredNullableDatetimeProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableDatetimeProp
@@ -762,7 +762,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
-        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = false)]
         public Guid RequiredNotnullableUuid { get; set; }
 
         /// <summary>
@@ -772,7 +772,7 @@ namespace Org.OpenAPITools.Model
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
         [DataMember(Name = "notrequired_nullable_uuid", EmitDefaultValue = true)]
-        public Guid? NotrequiredNullableUuid { get; set; }
+        public Guid?? NotrequiredNullableUuid { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableUuid
@@ -792,14 +792,14 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableArrayOfString
         /// </summary>
-        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = false)]
         public List<string> RequiredNotnullableArrayOfString { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNullableArrayOfString
         /// </summary>
         [DataMember(Name = "notrequired_nullable_array_of_string", EmitDefaultValue = true)]
-        public List<string> NotrequiredNullableArrayOfString { get; set; }
+        public List<string>? NotrequiredNullableArrayOfString { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableArrayOfString
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Return.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Return.cs
index ff745fb8c63..5caf01529f1 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Return.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Return.cs
@@ -45,7 +45,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets VarReturn
         /// </summary>
-        [DataMember(Name = "return", EmitDefaultValue = false)]
+        [DataMember(Name = "return", EmitDefaultValue = true)]
         public int VarReturn { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ScaleneTriangle.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
index a2f2a020ca0..a9f0145e073 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ShapeInterface.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ShapeInterface.cs
index f559e8b8052..141bf5a2beb 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ShapeInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ShapeInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
index c6845db92f2..68c27aea327 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/SpecialModelName.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/SpecialModelName.cs
index eba993bc6df..290f5eca496 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/SpecialModelName.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/SpecialModelName.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SpecialPropertyName
         /// </summary>
-        [DataMember(Name = "$special[property.name]", EmitDefaultValue = false)]
+        [DataMember(Name = "$special[property.name]", EmitDefaultValue = true)]
         public long SpecialPropertyName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Tag.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Tag.cs
index 662ad9138d5..f93e8b9dad3 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Tag.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Tag.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/TriangleInterface.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/TriangleInterface.cs
index 65b685735f9..90c1a907440 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/TriangleInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/TriangleInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/User.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/User.cs
index 20b349a6ded..f1285e6e975 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/User.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/User.cs
@@ -67,7 +67,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -110,7 +110,7 @@ namespace Org.OpenAPITools.Model
         /// User Status
         /// </summary>
         /// <value>User Status</value>
-        [DataMember(Name = "userStatus", EmitDefaultValue = false)]
+        [DataMember(Name = "userStatus", EmitDefaultValue = true)]
         public int UserStatus { get; set; }
 
         /// <summary>
@@ -125,21 +125,21 @@ namespace Org.OpenAPITools.Model
         /// </summary>
         /// <value>test code generation for nullable objects. Value must be a map of strings to values or the &#39;null&#39; value.</value>
         [DataMember(Name = "objectWithNoDeclaredPropsNullable", EmitDefaultValue = true)]
-        public Object ObjectWithNoDeclaredPropsNullable { get; set; }
+        public Object? ObjectWithNoDeclaredPropsNullable { get; set; }
 
         /// <summary>
         /// test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. See https://github.com/OAI/OpenAPI-Specification/issues/1389
         /// </summary>
         /// <value>test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. See https://github.com/OAI/OpenAPI-Specification/issues/1389</value>
         [DataMember(Name = "anyTypeProp", EmitDefaultValue = true)]
-        public Object AnyTypeProp { get; set; }
+        public Object? AnyTypeProp { get; set; }
 
         /// <summary>
         /// test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. The &#39;nullable&#39; attribute does not change the allowed values.
         /// </summary>
         /// <value>test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. The &#39;nullable&#39; attribute does not change the allowed values.</value>
         [DataMember(Name = "anyTypePropNullable", EmitDefaultValue = true)]
-        public Object AnyTypePropNullable { get; set; }
+        public Object? AnyTypePropNullable { get; set; }
 
         /// <summary>
         /// Gets or Sets additional properties
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Whale.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Whale.cs
index 85fe2d95bfe..192c7b77c41 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Whale.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Whale.cs
@@ -74,7 +74,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Zebra.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Zebra.cs
index 53ea6867b30..9f663bf753e 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Zebra.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/Zebra.cs
@@ -61,8 +61,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Type
         /// </summary>
-        [DataMember(Name = "type", EmitDefaultValue = false)]
-        public TypeEnum? Type { get; set; }
+        [DataMember(Name = "type", EmitDefaultValue = true)]
+        public TypeEnum Type { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Zebra" /> class.
         /// </summary>
@@ -91,7 +91,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
index 6fa1afb780b..731213824f1 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
@@ -55,8 +55,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ZeroBasedEnum
         /// </summary>
-        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = false)]
-        public ZeroBasedEnumEnum? ZeroBasedEnum { get; set; }
+        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = true)]
+        public ZeroBasedEnumEnum ZeroBasedEnum { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="ZeroBasedEnumClass" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Animal.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Animal.cs
index b6a28a7e3c9..698e3aadd71 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Animal.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Animal.cs
@@ -63,7 +63,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName
         {
             get{ return _ClassName;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ApiResponse.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ApiResponse.cs
index 616d4f5a451..436905115b8 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ApiResponse.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ApiResponse.cs
@@ -61,7 +61,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Code
         /// </summary>
-        [DataMember(Name = "code", EmitDefaultValue = false)]
+        [DataMember(Name = "code", EmitDefaultValue = true)]
         public int Code
         {
             get{ return _Code;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/AppleReq.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/AppleReq.cs
index 071709bc625..4cffa99eada 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/AppleReq.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/AppleReq.cs
@@ -60,7 +60,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Cultivar
         /// </summary>
-        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = false)]
         public string Cultivar
         {
             get{ return _Cultivar;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Banana.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Banana.cs
index 40effe24e76..74a25bd7b01 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Banana.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Banana.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets LengthCm
         /// </summary>
-        [DataMember(Name = "lengthCm", EmitDefaultValue = false)]
+        [DataMember(Name = "lengthCm", EmitDefaultValue = true)]
         public decimal LengthCm
         {
             get{ return _LengthCm;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/BasquePig.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/BasquePig.cs
index b3acb5950be..ebc870f7aef 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/BasquePig.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/BasquePig.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName
         {
             get{ return _ClassName;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Category.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Category.cs
index c15741a47c8..57c58b8b446 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Category.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Category.cs
@@ -64,7 +64,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id
         {
             get{ return _Id;}
@@ -88,7 +88,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name
         {
             get{ return _Name;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
index 40bc0fa6704..b11b8ba3c94 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
@@ -65,7 +65,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType
         {
             get{ return _ShapeType;}
@@ -89,7 +89,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType
         {
             get{ return _QuadrilateralType;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/CopyActivity.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/CopyActivity.cs
index 8484b5f0c9c..8b0a7fd4d37 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/CopyActivity.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/CopyActivity.cs
@@ -100,7 +100,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets CopyActivitytt
         /// </summary>
-        [DataMember(Name = "copyActivitytt", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "copyActivitytt", IsRequired = true, EmitDefaultValue = false)]
         public string CopyActivitytt
         {
             get{ return _CopyActivitytt;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/DanishPig.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/DanishPig.cs
index 583ace694eb..a90bda2f8ff 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/DanishPig.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/DanishPig.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName
         {
             get{ return _ClassName;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EntityBase.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EntityBase.cs
index cccad486fa3..0dde9e9c017 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EntityBase.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EntityBase.cs
@@ -61,7 +61,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Schema
         /// </summary>
-        [DataMember(Name = "$schema", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "$schema", IsRequired = true, EmitDefaultValue = false)]
         public string Schema
         {
             get{ return _Schema;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EnumArrays.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EnumArrays.cs
index 774f416dcae..d3acd1036a0 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EnumArrays.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EnumArrays.cs
@@ -56,8 +56,8 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets JustSymbol
         /// </summary>
 
-        [DataMember(Name = "just_symbol", EmitDefaultValue = false)]
-        public JustSymbolEnum? JustSymbol
+        [DataMember(Name = "just_symbol", EmitDefaultValue = true)]
+        public JustSymbolEnum JustSymbol
         {
             get{ return _JustSymbol;}
             set
@@ -66,7 +66,7 @@ namespace Org.OpenAPITools.Model
                 _flagJustSymbol = true;
             }
         }
-        private JustSymbolEnum? _JustSymbol;
+        private JustSymbolEnum _JustSymbol;
         private bool _flagJustSymbol;
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EnumTest.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EnumTest.cs
index e3fd5593c81..db86c26b3e8 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EnumTest.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EnumTest.cs
@@ -92,8 +92,8 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets EnumString
         /// </summary>
 
-        [DataMember(Name = "enum_string", EmitDefaultValue = false)]
-        public EnumStringEnum? EnumString
+        [DataMember(Name = "enum_string", EmitDefaultValue = true)]
+        public EnumStringEnum EnumString
         {
             get{ return _EnumString;}
             set
@@ -102,7 +102,7 @@ namespace Org.OpenAPITools.Model
                 _flagEnumString = true;
             }
         }
-        private EnumStringEnum? _EnumString;
+        private EnumStringEnum _EnumString;
         private bool _flagEnumString;
 
         /// <summary>
@@ -215,8 +215,8 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets EnumInteger
         /// </summary>
 
-        [DataMember(Name = "enum_integer", EmitDefaultValue = false)]
-        public EnumIntegerEnum? EnumInteger
+        [DataMember(Name = "enum_integer", EmitDefaultValue = true)]
+        public EnumIntegerEnum EnumInteger
         {
             get{ return _EnumInteger;}
             set
@@ -225,7 +225,7 @@ namespace Org.OpenAPITools.Model
                 _flagEnumInteger = true;
             }
         }
-        private EnumIntegerEnum? _EnumInteger;
+        private EnumIntegerEnum _EnumInteger;
         private bool _flagEnumInteger;
 
         /// <summary>
@@ -257,8 +257,8 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets EnumIntegerOnly
         /// </summary>
 
-        [DataMember(Name = "enum_integer_only", EmitDefaultValue = false)]
-        public EnumIntegerOnlyEnum? EnumIntegerOnly
+        [DataMember(Name = "enum_integer_only", EmitDefaultValue = true)]
+        public EnumIntegerOnlyEnum EnumIntegerOnly
         {
             get{ return _EnumIntegerOnly;}
             set
@@ -267,7 +267,7 @@ namespace Org.OpenAPITools.Model
                 _flagEnumIntegerOnly = true;
             }
         }
-        private EnumIntegerOnlyEnum? _EnumIntegerOnly;
+        private EnumIntegerOnlyEnum _EnumIntegerOnly;
         private bool _flagEnumIntegerOnly;
 
         /// <summary>
@@ -302,8 +302,8 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets EnumNumber
         /// </summary>
 
-        [DataMember(Name = "enum_number", EmitDefaultValue = false)]
-        public EnumNumberEnum? EnumNumber
+        [DataMember(Name = "enum_number", EmitDefaultValue = true)]
+        public EnumNumberEnum EnumNumber
         {
             get{ return _EnumNumber;}
             set
@@ -312,7 +312,7 @@ namespace Org.OpenAPITools.Model
                 _flagEnumNumber = true;
             }
         }
-        private EnumNumberEnum? _EnumNumber;
+        private EnumNumberEnum _EnumNumber;
         private bool _flagEnumNumber;
 
         /// <summary>
@@ -329,7 +329,7 @@ namespace Org.OpenAPITools.Model
         /// </summary>
 
         [DataMember(Name = "outerEnum", EmitDefaultValue = true)]
-        public OuterEnum? OuterEnum
+        public OuterEnum OuterEnum
         {
             get{ return _OuterEnum;}
             set
@@ -338,7 +338,7 @@ namespace Org.OpenAPITools.Model
                 _flagOuterEnum = true;
             }
         }
-        private OuterEnum? _OuterEnum;
+        private OuterEnum _OuterEnum;
         private bool _flagOuterEnum;
 
         /// <summary>
@@ -354,8 +354,8 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets OuterEnumInteger
         /// </summary>
 
-        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = false)]
-        public OuterEnumInteger? OuterEnumInteger
+        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = true)]
+        public OuterEnumInteger OuterEnumInteger
         {
             get{ return _OuterEnumInteger;}
             set
@@ -364,7 +364,7 @@ namespace Org.OpenAPITools.Model
                 _flagOuterEnumInteger = true;
             }
         }
-        private OuterEnumInteger? _OuterEnumInteger;
+        private OuterEnumInteger _OuterEnumInteger;
         private bool _flagOuterEnumInteger;
 
         /// <summary>
@@ -380,8 +380,8 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets OuterEnumDefaultValue
         /// </summary>
 
-        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? OuterEnumDefaultValue
+        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue OuterEnumDefaultValue
         {
             get{ return _OuterEnumDefaultValue;}
             set
@@ -390,7 +390,7 @@ namespace Org.OpenAPITools.Model
                 _flagOuterEnumDefaultValue = true;
             }
         }
-        private OuterEnumDefaultValue? _OuterEnumDefaultValue;
+        private OuterEnumDefaultValue _OuterEnumDefaultValue;
         private bool _flagOuterEnumDefaultValue;
 
         /// <summary>
@@ -406,8 +406,8 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets OuterEnumIntegerDefaultValue
         /// </summary>
 
-        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumIntegerDefaultValue? OuterEnumIntegerDefaultValue
+        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumIntegerDefaultValue OuterEnumIntegerDefaultValue
         {
             get{ return _OuterEnumIntegerDefaultValue;}
             set
@@ -416,7 +416,7 @@ namespace Org.OpenAPITools.Model
                 _flagOuterEnumIntegerDefaultValue = true;
             }
         }
-        private OuterEnumIntegerDefaultValue? _OuterEnumIntegerDefaultValue;
+        private OuterEnumIntegerDefaultValue _OuterEnumIntegerDefaultValue;
         private bool _flagOuterEnumIntegerDefaultValue;
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EquilateralTriangle.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
index 2b64977c4cb..a446cd2a1ce 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
@@ -65,7 +65,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType
         {
             get{ return _ShapeType;}
@@ -89,7 +89,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType
         {
             get{ return _TriangleType;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/FormatTest.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/FormatTest.cs
index c1d79614e1e..740c44a4ba5 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/FormatTest.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/FormatTest.cs
@@ -197,7 +197,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Integer
         /// </summary>
-        [DataMember(Name = "integer", EmitDefaultValue = false)]
+        [DataMember(Name = "integer", EmitDefaultValue = true)]
         public int Integer
         {
             get{ return _Integer;}
@@ -221,7 +221,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Int32
         /// </summary>
-        [DataMember(Name = "int32", EmitDefaultValue = false)]
+        [DataMember(Name = "int32", EmitDefaultValue = true)]
         public int Int32
         {
             get{ return _Int32;}
@@ -245,7 +245,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Int32Range
         /// </summary>
-        [DataMember(Name = "int32Range", EmitDefaultValue = false)]
+        [DataMember(Name = "int32Range", EmitDefaultValue = true)]
         public int Int32Range
         {
             get{ return _Int32Range;}
@@ -269,7 +269,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Int64Positive
         /// </summary>
-        [DataMember(Name = "int64Positive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64Positive", EmitDefaultValue = true)]
         public long Int64Positive
         {
             get{ return _Int64Positive;}
@@ -293,7 +293,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Int64Negative
         /// </summary>
-        [DataMember(Name = "int64Negative", EmitDefaultValue = false)]
+        [DataMember(Name = "int64Negative", EmitDefaultValue = true)]
         public long Int64Negative
         {
             get{ return _Int64Negative;}
@@ -317,7 +317,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Int64PositiveExclusive
         /// </summary>
-        [DataMember(Name = "int64PositiveExclusive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64PositiveExclusive", EmitDefaultValue = true)]
         public long Int64PositiveExclusive
         {
             get{ return _Int64PositiveExclusive;}
@@ -341,7 +341,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Int64NegativeExclusive
         /// </summary>
-        [DataMember(Name = "int64NegativeExclusive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64NegativeExclusive", EmitDefaultValue = true)]
         public long Int64NegativeExclusive
         {
             get{ return _Int64NegativeExclusive;}
@@ -365,7 +365,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets UnsignedInteger
         /// </summary>
-        [DataMember(Name = "unsigned_integer", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_integer", EmitDefaultValue = true)]
         public uint UnsignedInteger
         {
             get{ return _UnsignedInteger;}
@@ -389,7 +389,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Int64
         /// </summary>
-        [DataMember(Name = "int64", EmitDefaultValue = false)]
+        [DataMember(Name = "int64", EmitDefaultValue = true)]
         public long Int64
         {
             get{ return _Int64;}
@@ -413,7 +413,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets UnsignedLong
         /// </summary>
-        [DataMember(Name = "unsigned_long", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_long", EmitDefaultValue = true)]
         public ulong UnsignedLong
         {
             get{ return _UnsignedLong;}
@@ -461,7 +461,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Float
         /// </summary>
-        [DataMember(Name = "float", EmitDefaultValue = false)]
+        [DataMember(Name = "float", EmitDefaultValue = true)]
         public float Float
         {
             get{ return _Float;}
@@ -485,7 +485,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Double
         /// </summary>
-        [DataMember(Name = "double", EmitDefaultValue = false)]
+        [DataMember(Name = "double", EmitDefaultValue = true)]
         public double Double
         {
             get{ return _Double;}
@@ -509,7 +509,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Decimal
         /// </summary>
-        [DataMember(Name = "decimal", EmitDefaultValue = false)]
+        [DataMember(Name = "decimal", EmitDefaultValue = true)]
         public decimal Decimal
         {
             get{ return _Decimal;}
@@ -557,7 +557,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Byte
         /// </summary>
-        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = false)]
         public byte[] Byte
         {
             get{ return _Byte;}
@@ -609,7 +609,7 @@ namespace Org.OpenAPITools.Model
         <example>Sun Feb 02 00:00:00 UTC 2020</example>
         */
         [JsonConverter(typeof(OpenAPIDateConverter))]
-        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = false)]
         public DateTime Date
         {
             get{ return _Date;}
@@ -687,7 +687,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Password
         /// </summary>
-        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = false)]
         public string Password
         {
             get{ return _Password;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/GrandparentAnimal.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
index ab2e27672ef..e1588a08438 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
@@ -62,7 +62,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets PetType
         /// </summary>
-        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = false)]
         public string PetType
         {
             get{ return _PetType;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
index a552ae66464..f21a676d075 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
@@ -61,7 +61,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType
         {
             get{ return _ShapeType;}
@@ -85,7 +85,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType
         {
             get{ return _TriangleType;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Model200Response.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Model200Response.cs
index a04ab5a4b68..ad9f8bd89ab 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Model200Response.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Model200Response.cs
@@ -55,7 +55,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", EmitDefaultValue = false)]
+        [DataMember(Name = "name", EmitDefaultValue = true)]
         public int Name
         {
             get{ return _Name;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Name.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Name.cs
index e7055534004..1a3ce9d756c 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Name.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Name.cs
@@ -83,7 +83,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SnakeCase
         /// </summary>
-        [DataMember(Name = "snake_case", EmitDefaultValue = false)]
+        [DataMember(Name = "snake_case", EmitDefaultValue = true)]
         public int SnakeCase { get; private set; }
 
         /// <summary>
@@ -121,7 +121,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Var123Number
         /// </summary>
-        [DataMember(Name = "123Number", EmitDefaultValue = false)]
+        [DataMember(Name = "123Number", EmitDefaultValue = true)]
         public int Var123Number { get; private set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
index 227922a8fa1..dfc46c50e9d 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
@@ -84,7 +84,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets AObjVariableobject
         /// </summary>
-        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = false)]
         public List<Dictionary<string, Object>> AObjVariableobject
         {
             get{ return _AObjVariableobject;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/NumberOnly.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/NumberOnly.cs
index d5eeb462487..94b099af22e 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/NumberOnly.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/NumberOnly.cs
@@ -52,7 +52,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustNumber
         /// </summary>
-        [DataMember(Name = "JustNumber", EmitDefaultValue = false)]
+        [DataMember(Name = "JustNumber", EmitDefaultValue = true)]
         public decimal JustNumber
         {
             get{ return _JustNumber;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
index 411cdf8a15a..b1a13ea1e28 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
@@ -91,7 +91,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         [Obsolete]
         public decimal Id
         {
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Order.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Order.cs
index c660fee2288..c2df75aa7cf 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Order.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Order.cs
@@ -64,8 +64,8 @@ namespace Org.OpenAPITools.Model
         /// </summary>
         /// <value>Order Status</value>
 
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status
         {
             get{ return _Status;}
             set
@@ -74,7 +74,7 @@ namespace Org.OpenAPITools.Model
                 _flagStatus = true;
             }
         }
-        private StatusEnum? _Status;
+        private StatusEnum _Status;
         private bool _flagStatus;
 
         /// <summary>
@@ -127,7 +127,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id
         {
             get{ return _Id;}
@@ -151,7 +151,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets PetId
         /// </summary>
-        [DataMember(Name = "petId", EmitDefaultValue = false)]
+        [DataMember(Name = "petId", EmitDefaultValue = true)]
         public long PetId
         {
             get{ return _PetId;}
@@ -175,7 +175,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Quantity
         /// </summary>
-        [DataMember(Name = "quantity", EmitDefaultValue = false)]
+        [DataMember(Name = "quantity", EmitDefaultValue = true)]
         public int Quantity
         {
             get{ return _Quantity;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/OuterComposite.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/OuterComposite.cs
index a73853ef32e..ac44ff23588 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/OuterComposite.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/OuterComposite.cs
@@ -61,7 +61,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets MyNumber
         /// </summary>
-        [DataMember(Name = "my_number", EmitDefaultValue = false)]
+        [DataMember(Name = "my_number", EmitDefaultValue = true)]
         public decimal MyNumber
         {
             get{ return _MyNumber;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Pet.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Pet.cs
index beff340cf26..75fc1ef89a9 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Pet.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Pet.cs
@@ -64,8 +64,8 @@ namespace Org.OpenAPITools.Model
         /// </summary>
         /// <value>pet status in the store</value>
 
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status
         {
             get{ return _Status;}
             set
@@ -74,7 +74,7 @@ namespace Org.OpenAPITools.Model
                 _flagStatus = true;
             }
         }
-        private StatusEnum? _Status;
+        private StatusEnum _Status;
         private bool _flagStatus;
 
         /// <summary>
@@ -142,7 +142,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id
         {
             get{ return _Id;}
@@ -193,7 +193,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>doggie</example>
         */
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name
         {
             get{ return _Name;}
@@ -217,7 +217,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets PhotoUrls
         /// </summary>
-        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = false)]
         public List<string> PhotoUrls
         {
             get{ return _PhotoUrls;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
index 75995ecfa2d..3816ab7820a 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType
         {
             get{ return _QuadrilateralType;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/RequiredClass.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/RequiredClass.cs
index eafc6ff0b6c..8f19b53750d 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/RequiredClass.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/RequiredClass.cs
@@ -138,7 +138,7 @@ namespace Org.OpenAPITools.Model
         /// </summary>
 
         [DataMember(Name = "notrequired_nullable_enum_integer", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumIntegerEnum? NotrequiredNullableEnumInteger
+        public NotrequiredNullableEnumIntegerEnum NotrequiredNullableEnumInteger
         {
             get{ return _NotrequiredNullableEnumInteger;}
             set
@@ -147,7 +147,7 @@ namespace Org.OpenAPITools.Model
                 _flagNotrequiredNullableEnumInteger = true;
             }
         }
-        private NotrequiredNullableEnumIntegerEnum? _NotrequiredNullableEnumInteger;
+        private NotrequiredNullableEnumIntegerEnum _NotrequiredNullableEnumInteger;
         private bool _flagNotrequiredNullableEnumInteger;
 
         /// <summary>
@@ -179,8 +179,8 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNotnullableEnumInteger
         /// </summary>
 
-        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerEnum? NotrequiredNotnullableEnumInteger
+        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerEnum NotrequiredNotnullableEnumInteger
         {
             get{ return _NotrequiredNotnullableEnumInteger;}
             set
@@ -189,7 +189,7 @@ namespace Org.OpenAPITools.Model
                 _flagNotrequiredNotnullableEnumInteger = true;
             }
         }
-        private NotrequiredNotnullableEnumIntegerEnum? _NotrequiredNotnullableEnumInteger;
+        private NotrequiredNotnullableEnumIntegerEnum _NotrequiredNotnullableEnumInteger;
         private bool _flagNotrequiredNotnullableEnumInteger;
 
         /// <summary>
@@ -308,7 +308,7 @@ namespace Org.OpenAPITools.Model
         /// </summary>
 
         [DataMember(Name = "notrequired_nullable_enum_integer_only", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumIntegerOnlyEnum? NotrequiredNullableEnumIntegerOnly
+        public NotrequiredNullableEnumIntegerOnlyEnum NotrequiredNullableEnumIntegerOnly
         {
             get{ return _NotrequiredNullableEnumIntegerOnly;}
             set
@@ -317,7 +317,7 @@ namespace Org.OpenAPITools.Model
                 _flagNotrequiredNullableEnumIntegerOnly = true;
             }
         }
-        private NotrequiredNullableEnumIntegerOnlyEnum? _NotrequiredNullableEnumIntegerOnly;
+        private NotrequiredNullableEnumIntegerOnlyEnum _NotrequiredNullableEnumIntegerOnly;
         private bool _flagNotrequiredNullableEnumIntegerOnly;
 
         /// <summary>
@@ -349,8 +349,8 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
 
-        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerOnlyEnum? NotrequiredNotnullableEnumIntegerOnly
+        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerOnlyEnum NotrequiredNotnullableEnumIntegerOnly
         {
             get{ return _NotrequiredNotnullableEnumIntegerOnly;}
             set
@@ -359,7 +359,7 @@ namespace Org.OpenAPITools.Model
                 _flagNotrequiredNotnullableEnumIntegerOnly = true;
             }
         }
-        private NotrequiredNotnullableEnumIntegerOnlyEnum? _NotrequiredNotnullableEnumIntegerOnly;
+        private NotrequiredNotnullableEnumIntegerOnlyEnum _NotrequiredNotnullableEnumIntegerOnly;
         private bool _flagNotrequiredNotnullableEnumIntegerOnly;
 
         /// <summary>
@@ -593,7 +593,7 @@ namespace Org.OpenAPITools.Model
         /// </summary>
 
         [DataMember(Name = "notrequired_nullable_enum_string", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumStringEnum? NotrequiredNullableEnumString
+        public NotrequiredNullableEnumStringEnum NotrequiredNullableEnumString
         {
             get{ return _NotrequiredNullableEnumString;}
             set
@@ -602,7 +602,7 @@ namespace Org.OpenAPITools.Model
                 _flagNotrequiredNullableEnumString = true;
             }
         }
-        private NotrequiredNullableEnumStringEnum? _NotrequiredNullableEnumString;
+        private NotrequiredNullableEnumStringEnum _NotrequiredNullableEnumString;
         private bool _flagNotrequiredNullableEnumString;
 
         /// <summary>
@@ -673,8 +673,8 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNotnullableEnumString
         /// </summary>
 
-        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumStringEnum? NotrequiredNotnullableEnumString
+        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumStringEnum NotrequiredNotnullableEnumString
         {
             get{ return _NotrequiredNotnullableEnumString;}
             set
@@ -683,7 +683,7 @@ namespace Org.OpenAPITools.Model
                 _flagNotrequiredNotnullableEnumString = true;
             }
         }
-        private NotrequiredNotnullableEnumStringEnum? _NotrequiredNotnullableEnumString;
+        private NotrequiredNotnullableEnumStringEnum _NotrequiredNotnullableEnumString;
         private bool _flagNotrequiredNotnullableEnumString;
 
         /// <summary>
@@ -752,7 +752,7 @@ namespace Org.OpenAPITools.Model
         /// </summary>
 
         [DataMember(Name = "notrequired_nullable_outerEnumDefaultValue", EmitDefaultValue = true)]
-        public OuterEnumDefaultValue? NotrequiredNullableOuterEnumDefaultValue
+        public OuterEnumDefaultValue NotrequiredNullableOuterEnumDefaultValue
         {
             get{ return _NotrequiredNullableOuterEnumDefaultValue;}
             set
@@ -761,7 +761,7 @@ namespace Org.OpenAPITools.Model
                 _flagNotrequiredNullableOuterEnumDefaultValue = true;
             }
         }
-        private OuterEnumDefaultValue? _NotrequiredNullableOuterEnumDefaultValue;
+        private OuterEnumDefaultValue _NotrequiredNullableOuterEnumDefaultValue;
         private bool _flagNotrequiredNullableOuterEnumDefaultValue;
 
         /// <summary>
@@ -777,8 +777,8 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNotnullableOuterEnumDefaultValue
         /// </summary>
 
-        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? NotrequiredNotnullableOuterEnumDefaultValue
+        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue NotrequiredNotnullableOuterEnumDefaultValue
         {
             get{ return _NotrequiredNotnullableOuterEnumDefaultValue;}
             set
@@ -787,7 +787,7 @@ namespace Org.OpenAPITools.Model
                 _flagNotrequiredNotnullableOuterEnumDefaultValue = true;
             }
         }
-        private OuterEnumDefaultValue? _NotrequiredNotnullableOuterEnumDefaultValue;
+        private OuterEnumDefaultValue _NotrequiredNotnullableOuterEnumDefaultValue;
         private bool _flagNotrequiredNotnullableOuterEnumDefaultValue;
 
         /// <summary>
@@ -1110,7 +1110,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotRequiredNotnullableintegerProp
         /// </summary>
-        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = false)]
+        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = true)]
         public int NotRequiredNotnullableintegerProp
         {
             get{ return _NotRequiredNotnullableintegerProp;}
@@ -1158,7 +1158,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableStringProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = false)]
         public string RequiredNotnullableStringProp
         {
             get{ return _RequiredNotnullableStringProp;}
@@ -1352,7 +1352,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets RequiredNotNullableDateProp
         /// </summary>
         [JsonConverter(typeof(OpenAPIDateConverter))]
-        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateTime RequiredNotNullableDateProp
         {
             get{ return _RequiredNotNullableDateProp;}
@@ -1426,7 +1426,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableDatetimeProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateTime RequiredNotnullableDatetimeProp
         {
             get{ return _RequiredNotnullableDatetimeProp;}
@@ -1552,7 +1552,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
-        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = false)]
         public Guid RequiredNotnullableUuid
         {
             get{ return _RequiredNotnullableUuid;}
@@ -1654,7 +1654,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableArrayOfString
         /// </summary>
-        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = false)]
         public List<string> RequiredNotnullableArrayOfString
         {
             get{ return _RequiredNotnullableArrayOfString;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Return.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Return.cs
index b14f39f9b6b..6f35f1f1e18 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Return.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Return.cs
@@ -77,7 +77,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets VarReturn
         /// </summary>
-        [DataMember(Name = "return", EmitDefaultValue = false)]
+        [DataMember(Name = "return", EmitDefaultValue = true)]
         public int VarReturn
         {
             get{ return _VarReturn;}
@@ -101,7 +101,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Lock
         /// </summary>
-        [DataMember(Name = "lock", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "lock", IsRequired = true, EmitDefaultValue = false)]
         public string Lock
         {
             get{ return _Lock;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ScaleneTriangle.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
index f5bd010184d..99e96ed7909 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
@@ -65,7 +65,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType
         {
             get{ return _ShapeType;}
@@ -89,7 +89,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType
         {
             get{ return _TriangleType;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ShapeInterface.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ShapeInterface.cs
index f4d40aed5d6..090b72c57e8 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ShapeInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ShapeInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType
         {
             get{ return _ShapeType;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
index 0bed8c23130..c0f2314d84d 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
@@ -65,7 +65,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType
         {
             get{ return _ShapeType;}
@@ -89,7 +89,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType
         {
             get{ return _QuadrilateralType;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/SpecialModelName.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/SpecialModelName.cs
index bfb952dcd35..eea85df7dbb 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/SpecialModelName.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/SpecialModelName.cs
@@ -55,7 +55,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SpecialPropertyName
         /// </summary>
-        [DataMember(Name = "$special[property.name]", EmitDefaultValue = false)]
+        [DataMember(Name = "$special[property.name]", EmitDefaultValue = true)]
         public long SpecialPropertyName
         {
             get{ return _SpecialPropertyName;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Tag.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Tag.cs
index 71370874b76..04c593d31b1 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Tag.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Tag.cs
@@ -55,7 +55,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id
         {
             get{ return _Id;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/TriangleInterface.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/TriangleInterface.cs
index f37472cadd4..d39642f3e7f 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/TriangleInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/TriangleInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType
         {
             get{ return _TriangleType;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/User.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/User.cs
index 0d5b93e58ff..98c5bcecfa6 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/User.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/User.cs
@@ -115,7 +115,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id
         {
             get{ return _Id;}
@@ -284,7 +284,7 @@ namespace Org.OpenAPITools.Model
         /// User Status
         /// </summary>
         /// <value>User Status</value>
-        [DataMember(Name = "userStatus", EmitDefaultValue = false)]
+        [DataMember(Name = "userStatus", EmitDefaultValue = true)]
         public int UserStatus
         {
             get{ return _UserStatus;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Whale.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Whale.cs
index 1455bffc70d..90e47bfc8f5 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Whale.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Whale.cs
@@ -118,7 +118,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName
         {
             get{ return _ClassName;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Zebra.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Zebra.cs
index 9717a1ace7d..ec5c06d976b 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Zebra.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/Zebra.cs
@@ -62,8 +62,8 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets Type
         /// </summary>
 
-        [DataMember(Name = "type", EmitDefaultValue = false)]
-        public TypeEnum? Type
+        [DataMember(Name = "type", EmitDefaultValue = true)]
+        public TypeEnum Type
         {
             get{ return _Type;}
             set
@@ -72,7 +72,7 @@ namespace Org.OpenAPITools.Model
                 _flagType = true;
             }
         }
-        private TypeEnum? _Type;
+        private TypeEnum _Type;
         private bool _flagType;
 
         /// <summary>
@@ -115,7 +115,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName
         {
             get{ return _ClassName;}
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
index 262a2a49c3f..0522ad06300 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
@@ -56,8 +56,8 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets ZeroBasedEnum
         /// </summary>
 
-        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = false)]
-        public ZeroBasedEnumEnum? ZeroBasedEnum
+        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = true)]
+        public ZeroBasedEnumEnum ZeroBasedEnum
         {
             get{ return _ZeroBasedEnum;}
             set
@@ -66,7 +66,7 @@ namespace Org.OpenAPITools.Model
                 _flagZeroBasedEnum = true;
             }
         }
-        private ZeroBasedEnumEnum? _ZeroBasedEnum;
+        private ZeroBasedEnumEnum _ZeroBasedEnum;
         private bool _flagZeroBasedEnum;
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Animal.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Animal.cs
index f6d7f1cf5b6..30c944cff4d 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Animal.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Animal.cs
@@ -65,7 +65,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
index 7dec589c62d..06784267be7 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Code
         /// </summary>
-        [DataMember(Name = "code", EmitDefaultValue = false)]
+        [DataMember(Name = "code", EmitDefaultValue = true)]
         public int Code { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
index 15d96e2ee29..a5938afb489 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
@@ -56,7 +56,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Cultivar
         /// </summary>
-        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = false)]
         public string Cultivar { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Banana.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Banana.cs
index c506c26dbb8..dd2f1b89e91 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Banana.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Banana.cs
@@ -45,7 +45,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets LengthCm
         /// </summary>
-        [DataMember(Name = "lengthCm", EmitDefaultValue = false)]
+        [DataMember(Name = "lengthCm", EmitDefaultValue = true)]
         public decimal LengthCm { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
index bdb25571066..09e9a581bad 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Category.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Category.cs
index b56dfc0c482..1d5de514814 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Category.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Category.cs
@@ -60,13 +60,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
index b5cd8370cb9..663199a8867 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
index f3f19fce57f..7232c6d8fdb 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
index 7a9834a78d1..839aa9328bc 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
@@ -55,8 +55,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustSymbol
         /// </summary>
-        [DataMember(Name = "just_symbol", EmitDefaultValue = false)]
-        public JustSymbolEnum? JustSymbol { get; set; }
+        [DataMember(Name = "just_symbol", EmitDefaultValue = true)]
+        public JustSymbolEnum JustSymbol { get; set; }
         /// <summary>
         /// Defines ArrayEnum
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
index 0851264693b..38dbf965ee1 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
@@ -91,8 +91,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumString
         /// </summary>
-        [DataMember(Name = "enum_string", EmitDefaultValue = false)]
-        public EnumStringEnum? EnumString { get; set; }
+        [DataMember(Name = "enum_string", EmitDefaultValue = true)]
+        public EnumStringEnum EnumString { get; set; }
         /// <summary>
         /// Defines EnumStringRequired
         /// </summary>
@@ -174,8 +174,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumInteger
         /// </summary>
-        [DataMember(Name = "enum_integer", EmitDefaultValue = false)]
-        public EnumIntegerEnum? EnumInteger { get; set; }
+        [DataMember(Name = "enum_integer", EmitDefaultValue = true)]
+        public EnumIntegerEnum EnumInteger { get; set; }
         /// <summary>
         /// Defines EnumIntegerOnly
         /// </summary>
@@ -196,8 +196,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "enum_integer_only", EmitDefaultValue = false)]
-        public EnumIntegerOnlyEnum? EnumIntegerOnly { get; set; }
+        [DataMember(Name = "enum_integer_only", EmitDefaultValue = true)]
+        public EnumIntegerOnlyEnum EnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines EnumNumber
         /// </summary>
@@ -221,32 +221,32 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumNumber
         /// </summary>
-        [DataMember(Name = "enum_number", EmitDefaultValue = false)]
-        public EnumNumberEnum? EnumNumber { get; set; }
+        [DataMember(Name = "enum_number", EmitDefaultValue = true)]
+        public EnumNumberEnum EnumNumber { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnum
         /// </summary>
         [DataMember(Name = "outerEnum", EmitDefaultValue = true)]
-        public OuterEnum? OuterEnum { get; set; }
+        public OuterEnum OuterEnum { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumInteger
         /// </summary>
-        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = false)]
-        public OuterEnumInteger? OuterEnumInteger { get; set; }
+        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = true)]
+        public OuterEnumInteger OuterEnumInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? OuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue OuterEnumDefaultValue { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumIntegerDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumIntegerDefaultValue? OuterEnumIntegerDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumIntegerDefaultValue OuterEnumIntegerDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="EnumTest" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
index 373122a5923..cfb611876ad 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
index 08306695ce0..f7d5c6b450a 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
@@ -99,31 +99,31 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Integer
         /// </summary>
-        [DataMember(Name = "integer", EmitDefaultValue = false)]
+        [DataMember(Name = "integer", EmitDefaultValue = true)]
         public int Integer { get; set; }
 
         /// <summary>
         /// Gets or Sets Int32
         /// </summary>
-        [DataMember(Name = "int32", EmitDefaultValue = false)]
+        [DataMember(Name = "int32", EmitDefaultValue = true)]
         public int Int32 { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedInteger
         /// </summary>
-        [DataMember(Name = "unsigned_integer", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_integer", EmitDefaultValue = true)]
         public uint UnsignedInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64
         /// </summary>
-        [DataMember(Name = "int64", EmitDefaultValue = false)]
+        [DataMember(Name = "int64", EmitDefaultValue = true)]
         public long Int64 { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedLong
         /// </summary>
-        [DataMember(Name = "unsigned_long", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_long", EmitDefaultValue = true)]
         public ulong UnsignedLong { get; set; }
 
         /// <summary>
@@ -135,19 +135,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Float
         /// </summary>
-        [DataMember(Name = "float", EmitDefaultValue = false)]
+        [DataMember(Name = "float", EmitDefaultValue = true)]
         public float Float { get; set; }
 
         /// <summary>
         /// Gets or Sets Double
         /// </summary>
-        [DataMember(Name = "double", EmitDefaultValue = false)]
+        [DataMember(Name = "double", EmitDefaultValue = true)]
         public double Double { get; set; }
 
         /// <summary>
         /// Gets or Sets Decimal
         /// </summary>
-        [DataMember(Name = "decimal", EmitDefaultValue = false)]
+        [DataMember(Name = "decimal", EmitDefaultValue = true)]
         public decimal Decimal { get; set; }
 
         /// <summary>
@@ -159,7 +159,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Byte
         /// </summary>
-        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = false)]
         public byte[] Byte { get; set; }
 
         /// <summary>
@@ -174,7 +174,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>Sun Feb 02 00:00:00 UTC 2020</example>
         */
-        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = false)]
         [JsonConverter(typeof(OpenAPIDateConverter))]
         public DateTime Date { get; set; }
 
@@ -199,7 +199,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Password
         /// </summary>
-        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = false)]
         public string Password { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
index 9d576878b23..7763cc86a01 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
@@ -62,7 +62,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets PetType
         /// </summary>
-        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = false)]
         public string PetType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
index 297e82fd9ba..0594403a58a 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
@@ -61,13 +61,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
index 74b83092923..67b5b17e70f 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", EmitDefaultValue = false)]
+        [DataMember(Name = "name", EmitDefaultValue = true)]
         public int Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Name.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Name.cs
index 4eace322815..6d0af056430 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Name.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Name.cs
@@ -61,7 +61,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SnakeCase
         /// </summary>
-        [DataMember(Name = "snake_case", EmitDefaultValue = false)]
+        [DataMember(Name = "snake_case", EmitDefaultValue = true)]
         public int SnakeCase { get; private set; }
 
         /// <summary>
@@ -81,7 +81,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Var123Number
         /// </summary>
-        [DataMember(Name = "123Number", EmitDefaultValue = false)]
+        [DataMember(Name = "123Number", EmitDefaultValue = true)]
         public int Var123Number { get; private set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
index d99edd0c214..f87a4677aa0 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
@@ -66,7 +66,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets AObjVariableobject
         /// </summary>
-        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = false)]
         public List<Dictionary<string, Object>> AObjVariableobject { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
index cdfc6bae47e..741e520c489 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
@@ -48,7 +48,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustNumber
         /// </summary>
-        [DataMember(Name = "JustNumber", EmitDefaultValue = false)]
+        [DataMember(Name = "JustNumber", EmitDefaultValue = true)]
         public decimal JustNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
index a6fba6e93cc..31ac069c0f0 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
@@ -57,7 +57,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         [Obsolete]
         public decimal Id { get; set; }
 
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Order.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Order.cs
index 8aa03dd2f49..56dc1a0a656 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Order.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Order.cs
@@ -63,8 +63,8 @@ namespace Org.OpenAPITools.Model
         /// Order Status
         /// </summary>
         /// <value>Order Status</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Order" /> class.
         /// </summary>
@@ -88,19 +88,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets PetId
         /// </summary>
-        [DataMember(Name = "petId", EmitDefaultValue = false)]
+        [DataMember(Name = "petId", EmitDefaultValue = true)]
         public long PetId { get; set; }
 
         /// <summary>
         /// Gets or Sets Quantity
         /// </summary>
-        [DataMember(Name = "quantity", EmitDefaultValue = false)]
+        [DataMember(Name = "quantity", EmitDefaultValue = true)]
         public int Quantity { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
index f53ff933dab..9329f734ca9 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
@@ -49,7 +49,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets MyNumber
         /// </summary>
-        [DataMember(Name = "my_number", EmitDefaultValue = false)]
+        [DataMember(Name = "my_number", EmitDefaultValue = true)]
         public decimal MyNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Pet.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Pet.cs
index d6cf84c4d73..033d9f92351 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Pet.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Pet.cs
@@ -63,8 +63,8 @@ namespace Org.OpenAPITools.Model
         /// pet status in the store
         /// </summary>
         /// <value>pet status in the store</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Pet" /> class.
         /// </summary>
@@ -106,7 +106,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -121,13 +121,13 @@ namespace Org.OpenAPITools.Model
         /*
         <example>doggie</example>
         */
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
         /// Gets or Sets PhotoUrls
         /// </summary>
-        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = false)]
         public List<string> PhotoUrls { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
index c72cd676bb9..5311acc0977 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
index 596031f228f..26d3c570845 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
@@ -97,7 +97,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableEnumInteger
         /// </summary>
         [DataMember(Name = "notrequired_nullable_enum_integer", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumIntegerEnum? NotrequiredNullableEnumInteger { get; set; }
+        public NotrequiredNullableEnumIntegerEnum NotrequiredNullableEnumInteger { get; set; }
         /// <summary>
         /// Defines NotrequiredNotnullableEnumInteger
         /// </summary>
@@ -118,8 +118,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumInteger
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerEnum? NotrequiredNotnullableEnumInteger { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerEnum NotrequiredNotnullableEnumInteger { get; set; }
         /// <summary>
         /// Defines RequiredNullableEnumIntegerOnly
         /// </summary>
@@ -187,7 +187,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableEnumIntegerOnly
         /// </summary>
         [DataMember(Name = "notrequired_nullable_enum_integer_only", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumIntegerOnlyEnum? NotrequiredNullableEnumIntegerOnly { get; set; }
+        public NotrequiredNullableEnumIntegerOnlyEnum NotrequiredNullableEnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
@@ -208,8 +208,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerOnlyEnum? NotrequiredNotnullableEnumIntegerOnly { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerOnlyEnum NotrequiredNotnullableEnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines RequiredNotnullableEnumString
         /// </summary>
@@ -392,7 +392,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableEnumString
         /// </summary>
         [DataMember(Name = "notrequired_nullable_enum_string", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumStringEnum? NotrequiredNullableEnumString { get; set; }
+        public NotrequiredNullableEnumStringEnum NotrequiredNullableEnumString { get; set; }
         /// <summary>
         /// Defines NotrequiredNotnullableEnumString
         /// </summary>
@@ -452,8 +452,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumString
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumStringEnum? NotrequiredNotnullableEnumString { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumStringEnum NotrequiredNotnullableEnumString { get; set; }
 
         /// <summary>
         /// Gets or Sets RequiredNullableOuterEnumDefaultValue
@@ -471,13 +471,13 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableOuterEnumDefaultValue
         /// </summary>
         [DataMember(Name = "notrequired_nullable_outerEnumDefaultValue", EmitDefaultValue = true)]
-        public OuterEnumDefaultValue? NotrequiredNullableOuterEnumDefaultValue { get; set; }
+        public OuterEnumDefaultValue NotrequiredNullableOuterEnumDefaultValue { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableOuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="RequiredClass" /> class.
         /// </summary>
@@ -648,7 +648,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotRequiredNotnullableintegerProp
         /// </summary>
-        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = false)]
+        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = true)]
         public int NotRequiredNotnullableintegerProp { get; set; }
 
         /// <summary>
@@ -660,7 +660,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableStringProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = false)]
         public string RequiredNotnullableStringProp { get; set; }
 
         /// <summary>
@@ -709,7 +709,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotNullableDateProp
         /// </summary>
-        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = false)]
         [JsonConverter(typeof(OpenAPIDateConverter))]
         public DateTime RequiredNotNullableDateProp { get; set; }
 
@@ -730,7 +730,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableDatetimeProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateTime RequiredNotnullableDatetimeProp { get; set; }
 
         /// <summary>
@@ -766,7 +766,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
-        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = false)]
         public Guid RequiredNotnullableUuid { get; set; }
 
         /// <summary>
@@ -796,7 +796,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableArrayOfString
         /// </summary>
-        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = false)]
         public List<string> RequiredNotnullableArrayOfString { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Return.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Return.cs
index ff745fb8c63..5caf01529f1 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Return.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Return.cs
@@ -45,7 +45,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets VarReturn
         /// </summary>
-        [DataMember(Name = "return", EmitDefaultValue = false)]
+        [DataMember(Name = "return", EmitDefaultValue = true)]
         public int VarReturn { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
index a2f2a020ca0..a9f0145e073 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
index f559e8b8052..141bf5a2beb 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
index c6845db92f2..68c27aea327 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
@@ -65,13 +65,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
index eba993bc6df..290f5eca496 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SpecialPropertyName
         /// </summary>
-        [DataMember(Name = "$special[property.name]", EmitDefaultValue = false)]
+        [DataMember(Name = "$special[property.name]", EmitDefaultValue = true)]
         public long SpecialPropertyName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Tag.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Tag.cs
index 662ad9138d5..f93e8b9dad3 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Tag.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Tag.cs
@@ -47,7 +47,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
index 65b685735f9..90c1a907440 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
@@ -58,7 +58,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/User.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/User.cs
index 20b349a6ded..df1f607e5a7 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/User.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/User.cs
@@ -67,7 +67,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -110,7 +110,7 @@ namespace Org.OpenAPITools.Model
         /// User Status
         /// </summary>
         /// <value>User Status</value>
-        [DataMember(Name = "userStatus", EmitDefaultValue = false)]
+        [DataMember(Name = "userStatus", EmitDefaultValue = true)]
         public int UserStatus { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Whale.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Whale.cs
index 85fe2d95bfe..192c7b77c41 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Whale.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Whale.cs
@@ -74,7 +74,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Zebra.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
index 53ea6867b30..9f663bf753e 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
@@ -61,8 +61,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Type
         /// </summary>
-        [DataMember(Name = "type", EmitDefaultValue = false)]
-        public TypeEnum? Type { get; set; }
+        [DataMember(Name = "type", EmitDefaultValue = true)]
+        public TypeEnum Type { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Zebra" /> class.
         /// </summary>
@@ -91,7 +91,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
index 6fa1afb780b..731213824f1 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
@@ -55,8 +55,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ZeroBasedEnum
         /// </summary>
-        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = false)]
-        public ZeroBasedEnumEnum? ZeroBasedEnum { get; set; }
+        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = true)]
+        public ZeroBasedEnumEnum ZeroBasedEnum { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="ZeroBasedEnumClass" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs
index 7767821368d..f8445f664f9 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/AdditionalPropertiesClass.cs
@@ -69,7 +69,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets Anytype1
         /// </summary>
         [DataMember(Name = "anytype_1", EmitDefaultValue = true)]
-        public Object Anytype1 { get; set; }
+        public Object? Anytype1 { get; set; }
 
         /// <summary>
         /// Gets or Sets MapWithUndeclaredPropertiesAnytype1
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Animal.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Animal.cs
index c2969851e0f..3c2f68f1e65 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Animal.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Animal.cs
@@ -55,7 +55,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
index 39116917c0f..010719cb772 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
@@ -46,7 +46,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Code
         /// </summary>
-        [DataMember(Name = "code", EmitDefaultValue = false)]
+        [DataMember(Name = "code", EmitDefaultValue = true)]
         public int Code { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
index aceb828c481..e011bc6d373 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
@@ -54,7 +54,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Cultivar
         /// </summary>
-        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = false)]
         public string Cultivar { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Banana.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Banana.cs
index 7f92c5b6a63..91ebd0cf467 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Banana.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Banana.cs
@@ -42,7 +42,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets LengthCm
         /// </summary>
-        [DataMember(Name = "lengthCm", EmitDefaultValue = false)]
+        [DataMember(Name = "lengthCm", EmitDefaultValue = true)]
         public decimal LengthCm { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
index a7e890195e2..0f97ea616a3 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
@@ -52,7 +52,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Category.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Category.cs
index 5a27a006ed6..1a7c580ba47 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Category.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Category.cs
@@ -54,13 +54,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
index b7f8092edf9..fb7d3a8ea28 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
@@ -59,13 +59,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs
index bfb241c2444..c825d3e7f78 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs
@@ -73,7 +73,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets CopyActivitytt
         /// </summary>
-        [DataMember(Name = "copyActivitytt", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "copyActivitytt", IsRequired = true, EmitDefaultValue = false)]
         public string CopyActivitytt { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
index 808828b2e33..64df9006e27 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
@@ -52,7 +52,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Drawing.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Drawing.cs
index c2864540f6b..880b5d9e3d7 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Drawing.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Drawing.cs
@@ -56,13 +56,13 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets ShapeOrNull
         /// </summary>
         [DataMember(Name = "shapeOrNull", EmitDefaultValue = true)]
-        public ShapeOrNull ShapeOrNull { get; set; }
+        public ShapeOrNull? ShapeOrNull { get; set; }
 
         /// <summary>
         /// Gets or Sets NullableShape
         /// </summary>
         [DataMember(Name = "nullableShape", EmitDefaultValue = true)]
-        public NullableShape NullableShape { get; set; }
+        public NullableShape? NullableShape { get; set; }
 
         /// <summary>
         /// Gets or Sets Shapes
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs
index 0117119f39f..2897501aab9 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs
@@ -52,7 +52,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Schema
         /// </summary>
-        [DataMember(Name = "$schema", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "$schema", IsRequired = true, EmitDefaultValue = false)]
         public string Schema { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
index eed838f3a0e..c30bf6948f7 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
@@ -53,8 +53,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustSymbol
         /// </summary>
-        [DataMember(Name = "just_symbol", EmitDefaultValue = false)]
-        public JustSymbolEnum? JustSymbol { get; set; }
+        [DataMember(Name = "just_symbol", EmitDefaultValue = true)]
+        public JustSymbolEnum JustSymbol { get; set; }
         /// <summary>
         /// Defines ArrayEnum
         /// </summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
index 971635dad93..b928c4a7c4f 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
@@ -89,8 +89,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumString
         /// </summary>
-        [DataMember(Name = "enum_string", EmitDefaultValue = false)]
-        public EnumStringEnum? EnumString { get; set; }
+        [DataMember(Name = "enum_string", EmitDefaultValue = true)]
+        public EnumStringEnum EnumString { get; set; }
         /// <summary>
         /// Defines EnumStringRequired
         /// </summary>
@@ -172,8 +172,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumInteger
         /// </summary>
-        [DataMember(Name = "enum_integer", EmitDefaultValue = false)]
-        public EnumIntegerEnum? EnumInteger { get; set; }
+        [DataMember(Name = "enum_integer", EmitDefaultValue = true)]
+        public EnumIntegerEnum EnumInteger { get; set; }
         /// <summary>
         /// Defines EnumIntegerOnly
         /// </summary>
@@ -194,8 +194,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "enum_integer_only", EmitDefaultValue = false)]
-        public EnumIntegerOnlyEnum? EnumIntegerOnly { get; set; }
+        [DataMember(Name = "enum_integer_only", EmitDefaultValue = true)]
+        public EnumIntegerOnlyEnum EnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines EnumNumber
         /// </summary>
@@ -219,8 +219,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumNumber
         /// </summary>
-        [DataMember(Name = "enum_number", EmitDefaultValue = false)]
-        public EnumNumberEnum? EnumNumber { get; set; }
+        [DataMember(Name = "enum_number", EmitDefaultValue = true)]
+        public EnumNumberEnum EnumNumber { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnum
@@ -231,20 +231,20 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets OuterEnumInteger
         /// </summary>
-        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = false)]
-        public OuterEnumInteger? OuterEnumInteger { get; set; }
+        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = true)]
+        public OuterEnumInteger OuterEnumInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? OuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue OuterEnumDefaultValue { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumIntegerDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumIntegerDefaultValue? OuterEnumIntegerDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumIntegerDefaultValue OuterEnumIntegerDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="EnumTest" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
index 5d27bd6950c..f1f2e6ac316 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
@@ -59,13 +59,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
index 1affba019b0..45b78d50e72 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
@@ -107,61 +107,61 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Integer
         /// </summary>
-        [DataMember(Name = "integer", EmitDefaultValue = false)]
+        [DataMember(Name = "integer", EmitDefaultValue = true)]
         public int Integer { get; set; }
 
         /// <summary>
         /// Gets or Sets Int32
         /// </summary>
-        [DataMember(Name = "int32", EmitDefaultValue = false)]
+        [DataMember(Name = "int32", EmitDefaultValue = true)]
         public int Int32 { get; set; }
 
         /// <summary>
         /// Gets or Sets Int32Range
         /// </summary>
-        [DataMember(Name = "int32Range", EmitDefaultValue = false)]
+        [DataMember(Name = "int32Range", EmitDefaultValue = true)]
         public int Int32Range { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64Positive
         /// </summary>
-        [DataMember(Name = "int64Positive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64Positive", EmitDefaultValue = true)]
         public long Int64Positive { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64Negative
         /// </summary>
-        [DataMember(Name = "int64Negative", EmitDefaultValue = false)]
+        [DataMember(Name = "int64Negative", EmitDefaultValue = true)]
         public long Int64Negative { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64PositiveExclusive
         /// </summary>
-        [DataMember(Name = "int64PositiveExclusive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64PositiveExclusive", EmitDefaultValue = true)]
         public long Int64PositiveExclusive { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64NegativeExclusive
         /// </summary>
-        [DataMember(Name = "int64NegativeExclusive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64NegativeExclusive", EmitDefaultValue = true)]
         public long Int64NegativeExclusive { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedInteger
         /// </summary>
-        [DataMember(Name = "unsigned_integer", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_integer", EmitDefaultValue = true)]
         public uint UnsignedInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64
         /// </summary>
-        [DataMember(Name = "int64", EmitDefaultValue = false)]
+        [DataMember(Name = "int64", EmitDefaultValue = true)]
         public long Int64 { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedLong
         /// </summary>
-        [DataMember(Name = "unsigned_long", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_long", EmitDefaultValue = true)]
         public ulong UnsignedLong { get; set; }
 
         /// <summary>
@@ -173,19 +173,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Float
         /// </summary>
-        [DataMember(Name = "float", EmitDefaultValue = false)]
+        [DataMember(Name = "float", EmitDefaultValue = true)]
         public float Float { get; set; }
 
         /// <summary>
         /// Gets or Sets Double
         /// </summary>
-        [DataMember(Name = "double", EmitDefaultValue = false)]
+        [DataMember(Name = "double", EmitDefaultValue = true)]
         public double Double { get; set; }
 
         /// <summary>
         /// Gets or Sets Decimal
         /// </summary>
-        [DataMember(Name = "decimal", EmitDefaultValue = false)]
+        [DataMember(Name = "decimal", EmitDefaultValue = true)]
         public decimal Decimal { get; set; }
 
         /// <summary>
@@ -197,7 +197,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Byte
         /// </summary>
-        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = false)]
         public byte[] Byte { get; set; }
 
         /// <summary>
@@ -212,7 +212,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>Sun Feb 02 00:00:00 UTC 2020</example>
         */
-        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = false)]
         public DateOnly Date { get; set; }
 
         /// <summary>
@@ -236,7 +236,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Password
         /// </summary>
-        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = false)]
         public string Password { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
index 143f11802ee..57404796881 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
@@ -52,7 +52,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets PetType
         /// </summary>
-        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = false)]
         public string PetType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/HealthCheckResult.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/HealthCheckResult.cs
index 2637bc9d682..58fd384ed7b 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/HealthCheckResult.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/HealthCheckResult.cs
@@ -43,7 +43,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NullableMessage
         /// </summary>
         [DataMember(Name = "NullableMessage", EmitDefaultValue = true)]
-        public string NullableMessage { get; set; }
+        public string? NullableMessage { get; set; }
 
         /// <summary>
         /// Returns the string presentation of the object
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
index aea3de4e0a9..83075ca6611 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
@@ -59,13 +59,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
index e6aff544f30..da89058d2bc 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
@@ -44,7 +44,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", EmitDefaultValue = false)]
+        [DataMember(Name = "name", EmitDefaultValue = true)]
         public int Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Name.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Name.cs
index c7f491eeee6..de13fab30a7 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Name.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Name.cs
@@ -55,7 +55,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SnakeCase
         /// </summary>
-        [DataMember(Name = "snake_case", EmitDefaultValue = false)]
+        [DataMember(Name = "snake_case", EmitDefaultValue = true)]
         public int SnakeCase { get; private set; }
 
         /// <summary>
@@ -75,7 +75,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Var123Number
         /// </summary>
-        [DataMember(Name = "123Number", EmitDefaultValue = false)]
+        [DataMember(Name = "123Number", EmitDefaultValue = true)]
         public int Var123Number { get; private set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
index 04c54be4bf1..c78f90502b7 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
@@ -60,7 +60,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets AObjVariableobject
         /// </summary>
-        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = false)]
         public List<Dictionary<string, Object>> AObjVariableobject { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs
index fcd43ae049b..adbaaabe72b 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NullableClass.cs
@@ -66,49 +66,49 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets IntegerProp
         /// </summary>
         [DataMember(Name = "integer_prop", EmitDefaultValue = true)]
-        public int? IntegerProp { get; set; }
+        public int?? IntegerProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NumberProp
         /// </summary>
         [DataMember(Name = "number_prop", EmitDefaultValue = true)]
-        public decimal? NumberProp { get; set; }
+        public decimal?? NumberProp { get; set; }
 
         /// <summary>
         /// Gets or Sets BooleanProp
         /// </summary>
         [DataMember(Name = "boolean_prop", EmitDefaultValue = true)]
-        public bool? BooleanProp { get; set; }
+        public bool?? BooleanProp { get; set; }
 
         /// <summary>
         /// Gets or Sets StringProp
         /// </summary>
         [DataMember(Name = "string_prop", EmitDefaultValue = true)]
-        public string StringProp { get; set; }
+        public string? StringProp { get; set; }
 
         /// <summary>
         /// 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
         /// </summary>
         [DataMember(Name = "datetime_prop", EmitDefaultValue = true)]
-        public DateTime? DatetimeProp { get; set; }
+        public DateTime?? DatetimeProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayNullableProp
         /// </summary>
         [DataMember(Name = "array_nullable_prop", EmitDefaultValue = true)]
-        public List<Object> ArrayNullableProp { get; set; }
+        public List<Object>? ArrayNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayAndItemsNullableProp
         /// </summary>
         [DataMember(Name = "array_and_items_nullable_prop", EmitDefaultValue = true)]
-        public List<Object> ArrayAndItemsNullableProp { get; set; }
+        public List<Object>? ArrayAndItemsNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ArrayItemsNullable
@@ -120,13 +120,13 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets ObjectNullableProp
         /// </summary>
         [DataMember(Name = "object_nullable_prop", EmitDefaultValue = true)]
-        public Dictionary<string, Object> ObjectNullableProp { get; set; }
+        public Dictionary<string, Object>? ObjectNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ObjectAndItemsNullableProp
         /// </summary>
         [DataMember(Name = "object_and_items_nullable_prop", EmitDefaultValue = true)]
-        public Dictionary<string, Object> ObjectAndItemsNullableProp { get; set; }
+        public Dictionary<string, Object>? ObjectAndItemsNullableProp { get; set; }
 
         /// <summary>
         /// Gets or Sets ObjectItemsNullable
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NullableGuidClass.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NullableGuidClass.cs
index 04483a1f478..2e8196e6482 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NullableGuidClass.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NullableGuidClass.cs
@@ -46,7 +46,7 @@ namespace Org.OpenAPITools.Model
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
         [DataMember(Name = "uuid", EmitDefaultValue = true)]
-        public Guid? Uuid { get; set; }
+        public Guid?? Uuid { get; set; }
 
         /// <summary>
         /// Returns the string presentation of the object
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
index 63816553f0f..94816921ffd 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
@@ -45,7 +45,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustNumber
         /// </summary>
-        [DataMember(Name = "JustNumber", EmitDefaultValue = false)]
+        [DataMember(Name = "JustNumber", EmitDefaultValue = true)]
         public decimal JustNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
index 80da12c5d2c..49a24ee15f0 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
@@ -54,7 +54,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         [Obsolete]
         public decimal Id { get; set; }
 
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Order.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Order.cs
index f6ac07f1519..793c9c39529 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Order.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Order.cs
@@ -61,8 +61,8 @@ namespace Org.OpenAPITools.Model
         /// Order Status
         /// </summary>
         /// <value>Order Status</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Order" /> class.
         /// </summary>
@@ -85,19 +85,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets PetId
         /// </summary>
-        [DataMember(Name = "petId", EmitDefaultValue = false)]
+        [DataMember(Name = "petId", EmitDefaultValue = true)]
         public long PetId { get; set; }
 
         /// <summary>
         /// Gets or Sets Quantity
         /// </summary>
-        [DataMember(Name = "quantity", EmitDefaultValue = false)]
+        [DataMember(Name = "quantity", EmitDefaultValue = true)]
         public int Quantity { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
index 1b69c131555..b79bdb1ea70 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
@@ -46,7 +46,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets MyNumber
         /// </summary>
-        [DataMember(Name = "my_number", EmitDefaultValue = false)]
+        [DataMember(Name = "my_number", EmitDefaultValue = true)]
         public decimal MyNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Pet.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Pet.cs
index 6012561acb1..797bf3e662c 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Pet.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Pet.cs
@@ -61,8 +61,8 @@ namespace Org.OpenAPITools.Model
         /// pet status in the store
         /// </summary>
         /// <value>pet status in the store</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Pet" /> class.
         /// </summary>
@@ -100,7 +100,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -115,13 +115,13 @@ namespace Org.OpenAPITools.Model
         /*
         <example>doggie</example>
         */
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
         /// Gets or Sets PhotoUrls
         /// </summary>
-        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = false)]
         public List<string> PhotoUrls { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
index fb9ac03bb0f..539f8672195 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
@@ -52,7 +52,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
index a5cbbda329f..3a6ced6b362 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
@@ -116,8 +116,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumInteger
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerEnum? NotrequiredNotnullableEnumInteger { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerEnum NotrequiredNotnullableEnumInteger { get; set; }
         /// <summary>
         /// Defines RequiredNullableEnumIntegerOnly
         /// </summary>
@@ -206,8 +206,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerOnlyEnum? NotrequiredNotnullableEnumIntegerOnly { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerOnlyEnum NotrequiredNotnullableEnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines RequiredNotnullableEnumString
         /// </summary>
@@ -450,8 +450,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumString
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumStringEnum? NotrequiredNotnullableEnumString { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumStringEnum NotrequiredNotnullableEnumString { get; set; }
 
         /// <summary>
         /// Gets or Sets RequiredNullableOuterEnumDefaultValue
@@ -474,8 +474,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableOuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="RequiredClass" /> class.
         /// </summary>
@@ -637,12 +637,12 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotRequiredNullableIntegerProp
         /// </summary>
         [DataMember(Name = "not_required_nullable_integer_prop", EmitDefaultValue = true)]
-        public int? NotRequiredNullableIntegerProp { get; set; }
+        public int?? NotRequiredNullableIntegerProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotRequiredNotnullableintegerProp
         /// </summary>
-        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = false)]
+        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = true)]
         public int NotRequiredNotnullableintegerProp { get; set; }
 
         /// <summary>
@@ -654,14 +654,14 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableStringProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = false)]
         public string RequiredNotnullableStringProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNullableStringProp
         /// </summary>
         [DataMember(Name = "notrequired_nullable_string_prop", EmitDefaultValue = true)]
-        public string NotrequiredNullableStringProp { get; set; }
+        public string? NotrequiredNullableStringProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableStringProp
@@ -685,7 +685,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableBooleanProp
         /// </summary>
         [DataMember(Name = "notrequired_nullable_boolean_prop", EmitDefaultValue = true)]
-        public bool? NotrequiredNullableBooleanProp { get; set; }
+        public bool?? NotrequiredNullableBooleanProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableBooleanProp
@@ -702,14 +702,14 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotNullableDateProp
         /// </summary>
-        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateOnly RequiredNotNullableDateProp { get; set; }
 
         /// <summary>
         /// 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
@@ -720,7 +720,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableDatetimeProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateTime RequiredNotnullableDatetimeProp { get; set; }
 
         /// <summary>
@@ -733,7 +733,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableDatetimeProp
         /// </summary>
         [DataMember(Name = "notrequired_nullable_datetime_prop", EmitDefaultValue = true)]
-        public DateTime? NotrequiredNullableDatetimeProp { get; set; }
+        public DateTime?? NotrequiredNullableDatetimeProp { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableDatetimeProp
@@ -756,7 +756,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
-        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = false)]
         public Guid RequiredNotnullableUuid { get; set; }
 
         /// <summary>
@@ -766,7 +766,7 @@ namespace Org.OpenAPITools.Model
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
         [DataMember(Name = "notrequired_nullable_uuid", EmitDefaultValue = true)]
-        public Guid? NotrequiredNullableUuid { get; set; }
+        public Guid?? NotrequiredNullableUuid { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableUuid
@@ -786,14 +786,14 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableArrayOfString
         /// </summary>
-        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = false)]
         public List<string> RequiredNotnullableArrayOfString { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNullableArrayOfString
         /// </summary>
         [DataMember(Name = "notrequired_nullable_array_of_string", EmitDefaultValue = true)]
-        public List<string> NotrequiredNullableArrayOfString { get; set; }
+        public List<string>? NotrequiredNullableArrayOfString { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableArrayOfString
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Return.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Return.cs
index 4b101632d59..d33bf36092d 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Return.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Return.cs
@@ -63,13 +63,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets VarReturn
         /// </summary>
-        [DataMember(Name = "return", EmitDefaultValue = false)]
+        [DataMember(Name = "return", EmitDefaultValue = true)]
         public int VarReturn { get; set; }
 
         /// <summary>
         /// Gets or Sets Lock
         /// </summary>
-        [DataMember(Name = "lock", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "lock", IsRequired = true, EmitDefaultValue = false)]
         public string Lock { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
index 294cc1ec6fa..d5370079f00 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
@@ -59,13 +59,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
index 120446b7263..5d6b47cf283 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
@@ -52,7 +52,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
index e9f9506b850..cd1c71608b3 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
@@ -59,13 +59,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
index a654ab348e7..64b1f7eb506 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
@@ -44,7 +44,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SpecialPropertyName
         /// </summary>
-        [DataMember(Name = "$special[property.name]", EmitDefaultValue = false)]
+        [DataMember(Name = "$special[property.name]", EmitDefaultValue = true)]
         public long SpecialPropertyName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Tag.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Tag.cs
index a6838b8d1ac..4333d516d14 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Tag.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Tag.cs
@@ -44,7 +44,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
index b7ed99d6ffa..2dbd6a95761 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
@@ -52,7 +52,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/User.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/User.cs
index bc982332722..72048eee92a 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/User.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/User.cs
@@ -64,7 +64,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -107,7 +107,7 @@ namespace Org.OpenAPITools.Model
         /// User Status
         /// </summary>
         /// <value>User Status</value>
-        [DataMember(Name = "userStatus", EmitDefaultValue = false)]
+        [DataMember(Name = "userStatus", EmitDefaultValue = true)]
         public int UserStatus { get; set; }
 
         /// <summary>
@@ -122,21 +122,21 @@ namespace Org.OpenAPITools.Model
         /// </summary>
         /// <value>test code generation for nullable objects. Value must be a map of strings to values or the &#39;null&#39; value.</value>
         [DataMember(Name = "objectWithNoDeclaredPropsNullable", EmitDefaultValue = true)]
-        public Object ObjectWithNoDeclaredPropsNullable { get; set; }
+        public Object? ObjectWithNoDeclaredPropsNullable { get; set; }
 
         /// <summary>
         /// test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. See https://github.com/OAI/OpenAPI-Specification/issues/1389
         /// </summary>
         /// <value>test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. See https://github.com/OAI/OpenAPI-Specification/issues/1389</value>
         [DataMember(Name = "anyTypeProp", EmitDefaultValue = true)]
-        public Object AnyTypeProp { get; set; }
+        public Object? AnyTypeProp { get; set; }
 
         /// <summary>
         /// test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. The &#39;nullable&#39; attribute does not change the allowed values.
         /// </summary>
         /// <value>test code generation for any type Here the &#39;type&#39; attribute is not specified, which means the value can be anything, including the null value, string, number, boolean, array or object. The &#39;nullable&#39; attribute does not change the allowed values.</value>
         [DataMember(Name = "anyTypePropNullable", EmitDefaultValue = true)]
-        public Object AnyTypePropNullable { get; set; }
+        public Object? AnyTypePropNullable { get; set; }
 
         /// <summary>
         /// Returns the string presentation of the object
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Whale.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Whale.cs
index 5b4102b61db..e6f5f09f6c7 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Whale.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Whale.cs
@@ -68,7 +68,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Zebra.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
index 589273174e9..dc3311617af 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
@@ -59,8 +59,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Type
         /// </summary>
-        [DataMember(Name = "type", EmitDefaultValue = false)]
-        public TypeEnum? Type { get; set; }
+        [DataMember(Name = "type", EmitDefaultValue = true)]
+        public TypeEnum Type { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Zebra" /> class.
         /// </summary>
@@ -89,7 +89,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
index 841f5c9b15a..eaf50fd3724 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
@@ -53,8 +53,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ZeroBasedEnum
         /// </summary>
-        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = false)]
-        public ZeroBasedEnumEnum? ZeroBasedEnum { get; set; }
+        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = true)]
+        public ZeroBasedEnumEnum ZeroBasedEnum { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="ZeroBasedEnumClass" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Animal.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Animal.cs
index c2969851e0f..3c2f68f1e65 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Animal.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Animal.cs
@@ -55,7 +55,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
index 39116917c0f..010719cb772 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ApiResponse.cs
@@ -46,7 +46,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Code
         /// </summary>
-        [DataMember(Name = "code", EmitDefaultValue = false)]
+        [DataMember(Name = "code", EmitDefaultValue = true)]
         public int Code { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
index aceb828c481..e011bc6d373 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/AppleReq.cs
@@ -54,7 +54,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Cultivar
         /// </summary>
-        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "cultivar", IsRequired = true, EmitDefaultValue = false)]
         public string Cultivar { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Banana.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Banana.cs
index 7f92c5b6a63..91ebd0cf467 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Banana.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Banana.cs
@@ -42,7 +42,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets LengthCm
         /// </summary>
-        [DataMember(Name = "lengthCm", EmitDefaultValue = false)]
+        [DataMember(Name = "lengthCm", EmitDefaultValue = true)]
         public decimal LengthCm { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
index a7e890195e2..0f97ea616a3 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/BasquePig.cs
@@ -52,7 +52,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Category.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Category.cs
index 5a27a006ed6..1a7c580ba47 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Category.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Category.cs
@@ -54,13 +54,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
index b7f8092edf9..fb7d3a8ea28 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ComplexQuadrilateral.cs
@@ -59,13 +59,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs
index bfb241c2444..c825d3e7f78 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/CopyActivity.cs
@@ -73,7 +73,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets CopyActivitytt
         /// </summary>
-        [DataMember(Name = "copyActivitytt", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "copyActivitytt", IsRequired = true, EmitDefaultValue = false)]
         public string CopyActivitytt { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
index 808828b2e33..64df9006e27 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/DanishPig.cs
@@ -52,7 +52,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs
index 0117119f39f..2897501aab9 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EntityBase.cs
@@ -52,7 +52,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Schema
         /// </summary>
-        [DataMember(Name = "$schema", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "$schema", IsRequired = true, EmitDefaultValue = false)]
         public string Schema { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
index eed838f3a0e..c30bf6948f7 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumArrays.cs
@@ -53,8 +53,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustSymbol
         /// </summary>
-        [DataMember(Name = "just_symbol", EmitDefaultValue = false)]
-        public JustSymbolEnum? JustSymbol { get; set; }
+        [DataMember(Name = "just_symbol", EmitDefaultValue = true)]
+        public JustSymbolEnum JustSymbol { get; set; }
         /// <summary>
         /// Defines ArrayEnum
         /// </summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
index 971635dad93..e507aab8201 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EnumTest.cs
@@ -89,8 +89,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumString
         /// </summary>
-        [DataMember(Name = "enum_string", EmitDefaultValue = false)]
-        public EnumStringEnum? EnumString { get; set; }
+        [DataMember(Name = "enum_string", EmitDefaultValue = true)]
+        public EnumStringEnum EnumString { get; set; }
         /// <summary>
         /// Defines EnumStringRequired
         /// </summary>
@@ -172,8 +172,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumInteger
         /// </summary>
-        [DataMember(Name = "enum_integer", EmitDefaultValue = false)]
-        public EnumIntegerEnum? EnumInteger { get; set; }
+        [DataMember(Name = "enum_integer", EmitDefaultValue = true)]
+        public EnumIntegerEnum EnumInteger { get; set; }
         /// <summary>
         /// Defines EnumIntegerOnly
         /// </summary>
@@ -194,8 +194,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "enum_integer_only", EmitDefaultValue = false)]
-        public EnumIntegerOnlyEnum? EnumIntegerOnly { get; set; }
+        [DataMember(Name = "enum_integer_only", EmitDefaultValue = true)]
+        public EnumIntegerOnlyEnum EnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines EnumNumber
         /// </summary>
@@ -219,32 +219,32 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets EnumNumber
         /// </summary>
-        [DataMember(Name = "enum_number", EmitDefaultValue = false)]
-        public EnumNumberEnum? EnumNumber { get; set; }
+        [DataMember(Name = "enum_number", EmitDefaultValue = true)]
+        public EnumNumberEnum EnumNumber { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnum
         /// </summary>
         [DataMember(Name = "outerEnum", EmitDefaultValue = true)]
-        public OuterEnum? OuterEnum { get; set; }
+        public OuterEnum OuterEnum { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumInteger
         /// </summary>
-        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = false)]
-        public OuterEnumInteger? OuterEnumInteger { get; set; }
+        [DataMember(Name = "outerEnumInteger", EmitDefaultValue = true)]
+        public OuterEnumInteger OuterEnumInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? OuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue OuterEnumDefaultValue { get; set; }
 
         /// <summary>
         /// Gets or Sets OuterEnumIntegerDefaultValue
         /// </summary>
-        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumIntegerDefaultValue? OuterEnumIntegerDefaultValue { get; set; }
+        [DataMember(Name = "outerEnumIntegerDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumIntegerDefaultValue OuterEnumIntegerDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="EnumTest" /> class.
         /// </summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
index 5d27bd6950c..f1f2e6ac316 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/EquilateralTriangle.cs
@@ -59,13 +59,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
index 72cc4eb653f..4f5c9a572d8 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/FormatTest.cs
@@ -107,61 +107,61 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Integer
         /// </summary>
-        [DataMember(Name = "integer", EmitDefaultValue = false)]
+        [DataMember(Name = "integer", EmitDefaultValue = true)]
         public int Integer { get; set; }
 
         /// <summary>
         /// Gets or Sets Int32
         /// </summary>
-        [DataMember(Name = "int32", EmitDefaultValue = false)]
+        [DataMember(Name = "int32", EmitDefaultValue = true)]
         public int Int32 { get; set; }
 
         /// <summary>
         /// Gets or Sets Int32Range
         /// </summary>
-        [DataMember(Name = "int32Range", EmitDefaultValue = false)]
+        [DataMember(Name = "int32Range", EmitDefaultValue = true)]
         public int Int32Range { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64Positive
         /// </summary>
-        [DataMember(Name = "int64Positive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64Positive", EmitDefaultValue = true)]
         public long Int64Positive { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64Negative
         /// </summary>
-        [DataMember(Name = "int64Negative", EmitDefaultValue = false)]
+        [DataMember(Name = "int64Negative", EmitDefaultValue = true)]
         public long Int64Negative { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64PositiveExclusive
         /// </summary>
-        [DataMember(Name = "int64PositiveExclusive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64PositiveExclusive", EmitDefaultValue = true)]
         public long Int64PositiveExclusive { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64NegativeExclusive
         /// </summary>
-        [DataMember(Name = "int64NegativeExclusive", EmitDefaultValue = false)]
+        [DataMember(Name = "int64NegativeExclusive", EmitDefaultValue = true)]
         public long Int64NegativeExclusive { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedInteger
         /// </summary>
-        [DataMember(Name = "unsigned_integer", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_integer", EmitDefaultValue = true)]
         public uint UnsignedInteger { get; set; }
 
         /// <summary>
         /// Gets or Sets Int64
         /// </summary>
-        [DataMember(Name = "int64", EmitDefaultValue = false)]
+        [DataMember(Name = "int64", EmitDefaultValue = true)]
         public long Int64 { get; set; }
 
         /// <summary>
         /// Gets or Sets UnsignedLong
         /// </summary>
-        [DataMember(Name = "unsigned_long", EmitDefaultValue = false)]
+        [DataMember(Name = "unsigned_long", EmitDefaultValue = true)]
         public ulong UnsignedLong { get; set; }
 
         /// <summary>
@@ -173,19 +173,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Float
         /// </summary>
-        [DataMember(Name = "float", EmitDefaultValue = false)]
+        [DataMember(Name = "float", EmitDefaultValue = true)]
         public float Float { get; set; }
 
         /// <summary>
         /// Gets or Sets Double
         /// </summary>
-        [DataMember(Name = "double", EmitDefaultValue = false)]
+        [DataMember(Name = "double", EmitDefaultValue = true)]
         public double Double { get; set; }
 
         /// <summary>
         /// Gets or Sets Decimal
         /// </summary>
-        [DataMember(Name = "decimal", EmitDefaultValue = false)]
+        [DataMember(Name = "decimal", EmitDefaultValue = true)]
         public decimal Decimal { get; set; }
 
         /// <summary>
@@ -197,7 +197,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Byte
         /// </summary>
-        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "byte", IsRequired = true, EmitDefaultValue = false)]
         public byte[] Byte { get; set; }
 
         /// <summary>
@@ -212,7 +212,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>Sun Feb 02 00:00:00 UTC 2020</example>
         */
-        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "date", IsRequired = true, EmitDefaultValue = false)]
         [JsonConverter(typeof(OpenAPIDateConverter))]
         public DateTime Date { get; set; }
 
@@ -237,7 +237,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Password
         /// </summary>
-        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "password", IsRequired = true, EmitDefaultValue = false)]
         public string Password { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
index 143f11802ee..57404796881 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/GrandparentAnimal.cs
@@ -52,7 +52,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets PetType
         /// </summary>
-        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "pet_type", IsRequired = true, EmitDefaultValue = false)]
         public string PetType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
index aea3de4e0a9..83075ca6611 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/IsoscelesTriangle.cs
@@ -59,13 +59,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
index e6aff544f30..da89058d2bc 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Model200Response.cs
@@ -44,7 +44,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Name
         /// </summary>
-        [DataMember(Name = "name", EmitDefaultValue = false)]
+        [DataMember(Name = "name", EmitDefaultValue = true)]
         public int Name { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Name.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Name.cs
index c7f491eeee6..de13fab30a7 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Name.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Name.cs
@@ -55,7 +55,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SnakeCase
         /// </summary>
-        [DataMember(Name = "snake_case", EmitDefaultValue = false)]
+        [DataMember(Name = "snake_case", EmitDefaultValue = true)]
         public int SnakeCase { get; private set; }
 
         /// <summary>
@@ -75,7 +75,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Var123Number
         /// </summary>
-        [DataMember(Name = "123Number", EmitDefaultValue = false)]
+        [DataMember(Name = "123Number", EmitDefaultValue = true)]
         public int Var123Number { get; private set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
index 04c54be4bf1..c78f90502b7 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/NotificationtestGetElementsV1ResponseMPayload.cs
@@ -60,7 +60,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets AObjVariableobject
         /// </summary>
-        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "a_objVariableobject", IsRequired = true, EmitDefaultValue = false)]
         public List<Dictionary<string, Object>> AObjVariableobject { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
index 63816553f0f..94816921ffd 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/NumberOnly.cs
@@ -45,7 +45,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets JustNumber
         /// </summary>
-        [DataMember(Name = "JustNumber", EmitDefaultValue = false)]
+        [DataMember(Name = "JustNumber", EmitDefaultValue = true)]
         public decimal JustNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
index 80da12c5d2c..49a24ee15f0 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ObjectWithDeprecatedFields.cs
@@ -54,7 +54,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         [Obsolete]
         public decimal Id { get; set; }
 
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Order.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Order.cs
index f6ac07f1519..793c9c39529 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Order.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Order.cs
@@ -61,8 +61,8 @@ namespace Org.OpenAPITools.Model
         /// Order Status
         /// </summary>
         /// <value>Order Status</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Order" /> class.
         /// </summary>
@@ -85,19 +85,19 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
         /// Gets or Sets PetId
         /// </summary>
-        [DataMember(Name = "petId", EmitDefaultValue = false)]
+        [DataMember(Name = "petId", EmitDefaultValue = true)]
         public long PetId { get; set; }
 
         /// <summary>
         /// Gets or Sets Quantity
         /// </summary>
-        [DataMember(Name = "quantity", EmitDefaultValue = false)]
+        [DataMember(Name = "quantity", EmitDefaultValue = true)]
         public int Quantity { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
index 1b69c131555..b79bdb1ea70 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/OuterComposite.cs
@@ -46,7 +46,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets MyNumber
         /// </summary>
-        [DataMember(Name = "my_number", EmitDefaultValue = false)]
+        [DataMember(Name = "my_number", EmitDefaultValue = true)]
         public decimal MyNumber { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Pet.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Pet.cs
index 6012561acb1..797bf3e662c 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Pet.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Pet.cs
@@ -61,8 +61,8 @@ namespace Org.OpenAPITools.Model
         /// pet status in the store
         /// </summary>
         /// <value>pet status in the store</value>
-        [DataMember(Name = "status", EmitDefaultValue = false)]
-        public StatusEnum? Status { get; set; }
+        [DataMember(Name = "status", EmitDefaultValue = true)]
+        public StatusEnum Status { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Pet" /> class.
         /// </summary>
@@ -100,7 +100,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -115,13 +115,13 @@ namespace Org.OpenAPITools.Model
         /*
         <example>doggie</example>
         */
-        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "name", IsRequired = true, EmitDefaultValue = false)]
         public string Name { get; set; }
 
         /// <summary>
         /// Gets or Sets PhotoUrls
         /// </summary>
-        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "photoUrls", IsRequired = true, EmitDefaultValue = false)]
         public List<string> PhotoUrls { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
index fb9ac03bb0f..539f8672195 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/QuadrilateralInterface.cs
@@ -52,7 +52,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
index 2d5d949322d..0e130336d43 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/RequiredClass.cs
@@ -95,7 +95,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableEnumInteger
         /// </summary>
         [DataMember(Name = "notrequired_nullable_enum_integer", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumIntegerEnum? NotrequiredNullableEnumInteger { get; set; }
+        public NotrequiredNullableEnumIntegerEnum NotrequiredNullableEnumInteger { get; set; }
         /// <summary>
         /// Defines NotrequiredNotnullableEnumInteger
         /// </summary>
@@ -116,8 +116,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumInteger
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerEnum? NotrequiredNotnullableEnumInteger { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerEnum NotrequiredNotnullableEnumInteger { get; set; }
         /// <summary>
         /// Defines RequiredNullableEnumIntegerOnly
         /// </summary>
@@ -185,7 +185,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableEnumIntegerOnly
         /// </summary>
         [DataMember(Name = "notrequired_nullable_enum_integer_only", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumIntegerOnlyEnum? NotrequiredNullableEnumIntegerOnly { get; set; }
+        public NotrequiredNullableEnumIntegerOnlyEnum NotrequiredNullableEnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
@@ -206,8 +206,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumIntegerOnly
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumIntegerOnlyEnum? NotrequiredNotnullableEnumIntegerOnly { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_integer_only", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumIntegerOnlyEnum NotrequiredNotnullableEnumIntegerOnly { get; set; }
         /// <summary>
         /// Defines RequiredNotnullableEnumString
         /// </summary>
@@ -390,7 +390,7 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableEnumString
         /// </summary>
         [DataMember(Name = "notrequired_nullable_enum_string", EmitDefaultValue = true)]
-        public NotrequiredNullableEnumStringEnum? NotrequiredNullableEnumString { get; set; }
+        public NotrequiredNullableEnumStringEnum NotrequiredNullableEnumString { get; set; }
         /// <summary>
         /// Defines NotrequiredNotnullableEnumString
         /// </summary>
@@ -450,8 +450,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableEnumString
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = false)]
-        public NotrequiredNotnullableEnumStringEnum? NotrequiredNotnullableEnumString { get; set; }
+        [DataMember(Name = "notrequired_notnullable_enum_string", EmitDefaultValue = true)]
+        public NotrequiredNotnullableEnumStringEnum NotrequiredNotnullableEnumString { get; set; }
 
         /// <summary>
         /// Gets or Sets RequiredNullableOuterEnumDefaultValue
@@ -469,13 +469,13 @@ namespace Org.OpenAPITools.Model
         /// Gets or Sets NotrequiredNullableOuterEnumDefaultValue
         /// </summary>
         [DataMember(Name = "notrequired_nullable_outerEnumDefaultValue", EmitDefaultValue = true)]
-        public OuterEnumDefaultValue? NotrequiredNullableOuterEnumDefaultValue { get; set; }
+        public OuterEnumDefaultValue NotrequiredNullableOuterEnumDefaultValue { get; set; }
 
         /// <summary>
         /// Gets or Sets NotrequiredNotnullableOuterEnumDefaultValue
         /// </summary>
-        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = false)]
-        public OuterEnumDefaultValue? NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
+        [DataMember(Name = "notrequired_notnullable_outerEnumDefaultValue", EmitDefaultValue = true)]
+        public OuterEnumDefaultValue NotrequiredNotnullableOuterEnumDefaultValue { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="RequiredClass" /> class.
         /// </summary>
@@ -642,7 +642,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets NotRequiredNotnullableintegerProp
         /// </summary>
-        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = false)]
+        [DataMember(Name = "not_required_notnullableinteger_prop", EmitDefaultValue = true)]
         public int NotRequiredNotnullableintegerProp { get; set; }
 
         /// <summary>
@@ -654,7 +654,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableStringProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_string_prop", IsRequired = true, EmitDefaultValue = false)]
         public string RequiredNotnullableStringProp { get; set; }
 
         /// <summary>
@@ -703,7 +703,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotNullableDateProp
         /// </summary>
-        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_not_nullable_date_prop", IsRequired = true, EmitDefaultValue = false)]
         [JsonConverter(typeof(OpenAPIDateConverter))]
         public DateTime RequiredNotNullableDateProp { get; set; }
 
@@ -724,7 +724,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableDatetimeProp
         /// </summary>
-        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_datetime_prop", IsRequired = true, EmitDefaultValue = false)]
         public DateTime RequiredNotnullableDatetimeProp { get; set; }
 
         /// <summary>
@@ -760,7 +760,7 @@ namespace Org.OpenAPITools.Model
         /*
         <example>72f98069-206d-4f12-9f12-3d1e525a8e84</example>
         */
-        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_uuid", IsRequired = true, EmitDefaultValue = false)]
         public Guid RequiredNotnullableUuid { get; set; }
 
         /// <summary>
@@ -790,7 +790,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets RequiredNotnullableArrayOfString
         /// </summary>
-        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "required_notnullable_array_of_string", IsRequired = true, EmitDefaultValue = false)]
         public List<string> RequiredNotnullableArrayOfString { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Return.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Return.cs
index 4b101632d59..d33bf36092d 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Return.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Return.cs
@@ -63,13 +63,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets VarReturn
         /// </summary>
-        [DataMember(Name = "return", EmitDefaultValue = false)]
+        [DataMember(Name = "return", EmitDefaultValue = true)]
         public int VarReturn { get; set; }
 
         /// <summary>
         /// Gets or Sets Lock
         /// </summary>
-        [DataMember(Name = "lock", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "lock", IsRequired = true, EmitDefaultValue = false)]
         public string Lock { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
index 294cc1ec6fa..d5370079f00 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ScaleneTriangle.cs
@@ -59,13 +59,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
index 120446b7263..5d6b47cf283 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ShapeInterface.cs
@@ -52,7 +52,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
index e9f9506b850..cd1c71608b3 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/SimpleQuadrilateral.cs
@@ -59,13 +59,13 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ShapeType
         /// </summary>
-        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "shapeType", IsRequired = true, EmitDefaultValue = false)]
         public string ShapeType { get; set; }
 
         /// <summary>
         /// Gets or Sets QuadrilateralType
         /// </summary>
-        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "quadrilateralType", IsRequired = true, EmitDefaultValue = false)]
         public string QuadrilateralType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
index a654ab348e7..64b1f7eb506 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/SpecialModelName.cs
@@ -44,7 +44,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets SpecialPropertyName
         /// </summary>
-        [DataMember(Name = "$special[property.name]", EmitDefaultValue = false)]
+        [DataMember(Name = "$special[property.name]", EmitDefaultValue = true)]
         public long SpecialPropertyName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Tag.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Tag.cs
index a6838b8d1ac..4333d516d14 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Tag.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Tag.cs
@@ -44,7 +44,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
index b7ed99d6ffa..2dbd6a95761 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/TriangleInterface.cs
@@ -52,7 +52,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets TriangleType
         /// </summary>
-        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "triangleType", IsRequired = true, EmitDefaultValue = false)]
         public string TriangleType { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/User.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/User.cs
index bc982332722..6a0ba1cca38 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/User.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/User.cs
@@ -64,7 +64,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Id
         /// </summary>
-        [DataMember(Name = "id", EmitDefaultValue = false)]
+        [DataMember(Name = "id", EmitDefaultValue = true)]
         public long Id { get; set; }
 
         /// <summary>
@@ -107,7 +107,7 @@ namespace Org.OpenAPITools.Model
         /// User Status
         /// </summary>
         /// <value>User Status</value>
-        [DataMember(Name = "userStatus", EmitDefaultValue = false)]
+        [DataMember(Name = "userStatus", EmitDefaultValue = true)]
         public int UserStatus { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Whale.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Whale.cs
index 5b4102b61db..e6f5f09f6c7 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Whale.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Whale.cs
@@ -68,7 +68,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Zebra.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
index 589273174e9..dc3311617af 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/Zebra.cs
@@ -59,8 +59,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets Type
         /// </summary>
-        [DataMember(Name = "type", EmitDefaultValue = false)]
-        public TypeEnum? Type { get; set; }
+        [DataMember(Name = "type", EmitDefaultValue = true)]
+        public TypeEnum Type { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="Zebra" /> class.
         /// </summary>
@@ -89,7 +89,7 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ClassName
         /// </summary>
-        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = true)]
+        [DataMember(Name = "className", IsRequired = true, EmitDefaultValue = false)]
         public string ClassName { get; set; }
 
         /// <summary>
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
index 841f5c9b15a..eaf50fd3724 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Model/ZeroBasedEnumClass.cs
@@ -53,8 +53,8 @@ namespace Org.OpenAPITools.Model
         /// <summary>
         /// Gets or Sets ZeroBasedEnum
         /// </summary>
-        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = false)]
-        public ZeroBasedEnumEnum? ZeroBasedEnum { get; set; }
+        [DataMember(Name = "ZeroBasedEnum", EmitDefaultValue = true)]
+        public ZeroBasedEnumEnum ZeroBasedEnum { get; set; }
         /// <summary>
         /// Initializes a new instance of the <see cref="ZeroBasedEnumClass" /> class.
         /// </summary>