diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenProperty.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenProperty.java
index d80bc38a4c7..2808c9dcc2a 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenProperty.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenProperty.java
@@ -177,6 +177,9 @@ public class CodegenProperty {
         if (this.isEnum != other.isEnum) {
             return false;
         }
+        if (this.isReadOnly != other.isReadOnly && (this.isReadOnly == null || !this.isReadOnly.equals(other.isReadOnly))) {
+            return false;
+        }
         if (this._enum != other._enum && (this._enum == null || !this._enum.equals(other._enum))) {
             return false;
         }
diff --git a/modules/swagger-codegen/src/main/resources/csharp/model.mustache b/modules/swagger-codegen/src/main/resources/csharp/model.mustache
index 6abd76ce9df..85aecb25c2c 100644
--- a/modules/swagger-codegen/src/main/resources/csharp/model.mustache
+++ b/modules/swagger-codegen/src/main/resources/csharp/model.mustache
@@ -22,9 +22,25 @@ namespace {{packageName}}.Model
         /// <summary>
         /// Initializes a new instance of the <see cref="{{classname}}" /> class.
         /// </summary>
-        public {{classname}}()
+        public {{classname}}({{#vars}}{{{dataType}}}{{name}} = null{{#hasMore}}, {{/hasMore}}{{/vars}})
         {
-            {{#vars}}{{#defaultValue}}this.{{name}} = {{{defaultValue}}};
+            {{#vars}}{{#required}}if ({{name}} == null)
+            {
+                throw new InvalidDataException("{{name}} is a required property for {{classname}} and cannot be null");
+            }
+            else
+            {
+                this.{{name}} = {{name}};
+            }
+            {{/required}}{{/vars}}
+            {{#vars}}{{#defaultValue}}if ({{name}} == null) 
+            {
+                this.{{name}} = {{{defaultValue}}};
+            }
+            else 
+            {
+                this.{{name}} = {{name}};
+            }
             {{/defaultValue}}{{/vars}}
         }
 
@@ -34,7 +50,7 @@ namespace {{packageName}}.Model
         /// </summary>{{#description}}
         /// <value>{{{description}}}</value>{{/description}}
         [DataMember(Name="{{baseName}}", EmitDefaultValue=false)]
-        public {{{datatype}}} {{name}} { get; set; }
+        public {{{datatype}}} {{name}} { get; {{^isReadOnly}}set;{{/isReadOnly}} }
   
         {{/vars}}
   
diff --git a/modules/swagger-codegen/src/test/resources/2_0/petstore.json b/modules/swagger-codegen/src/test/resources/2_0/petstore.json
index b49bd81631e..6df7d079a10 100644
--- a/modules/swagger-codegen/src/test/resources/2_0/petstore.json
+++ b/modules/swagger-codegen/src/test/resources/2_0/petstore.json
@@ -1069,7 +1069,8 @@
       "properties": {
         "id": {
           "type": "integer",
-          "format": "int64"
+          "format": "int64",
+          "readOnly": true
         },
         "petId": {
           "type": "integer",
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Api/PetApi.cs b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Api/PetApi.cs
index 5ef6e286a8d..83f6558986d 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Api/PetApi.cs
@@ -1304,6 +1304,13 @@ namespace IO.Swagger.Api
             }
             // authentication (petstore_auth) required
             
+            // oauth required
+            if (!String.IsNullOrEmpty(Configuration.AccessToken))
+            {
+                headerParams["Authorization"] = "Bearer " + Configuration.AccessToken;
+            }
+            // authentication (petstore_auth) required
+            
             // oauth required
             if (!String.IsNullOrEmpty(Configuration.AccessToken))
             {
@@ -1404,6 +1411,14 @@ namespace IO.Swagger.Api
                 headerParams["Authorization"] = "Bearer " + Configuration.AccessToken;
             }
             
+            // authentication (petstore_auth) required
+            
+            // oauth required
+            if (!String.IsNullOrEmpty(Configuration.AccessToken))
+            {
+                headerParams["Authorization"] = "Bearer " + Configuration.AccessToken;
+            }
+            
 
             // make the HTTP request
             IRestResponse response = (IRestResponse) await Configuration.ApiClient.CallApiAsync(path_, 
@@ -2033,6 +2048,13 @@ namespace IO.Swagger.Api
             }
             // authentication (petstore_auth) required
             
+            // oauth required
+            if (!String.IsNullOrEmpty(Configuration.AccessToken))
+            {
+                headerParams["Authorization"] = "Bearer " + Configuration.AccessToken;
+            }
+            // authentication (petstore_auth) required
+            
             // oauth required
             if (!String.IsNullOrEmpty(Configuration.AccessToken))
             {
@@ -2133,6 +2155,14 @@ namespace IO.Swagger.Api
                 headerParams["Authorization"] = "Bearer " + Configuration.AccessToken;
             }
             
+            // authentication (petstore_auth) required
+            
+            // oauth required
+            if (!String.IsNullOrEmpty(Configuration.AccessToken))
+            {
+                headerParams["Authorization"] = "Bearer " + Configuration.AccessToken;
+            }
+            
 
             // make the HTTP request
             IRestResponse response = (IRestResponse) await Configuration.ApiClient.CallApiAsync(path_, 
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Api/StoreApi.cs b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Api/StoreApi.cs
index 914e28dd6fb..eac2760d98b 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Api/StoreApi.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Api/StoreApi.cs
@@ -676,7 +676,6 @@ namespace IO.Swagger.Api
             
 
             // authentication (test_api_key_header) required
-            
             if (!String.IsNullOrEmpty(Configuration.GetApiKeyWithPrefix("test_api_key_header")))
             {
                 headerParams["test_api_key_header"] = Configuration.GetApiKeyWithPrefix("test_api_key_header");
@@ -768,14 +767,12 @@ namespace IO.Swagger.Api
 
             
             // authentication (test_api_key_header) required
-            
             if (!String.IsNullOrEmpty(Configuration.GetApiKeyWithPrefix("test_api_key_header")))
             {
                 headerParams["test_api_key_header"] = Configuration.GetApiKeyWithPrefix("test_api_key_header");
             }
             
             // authentication (test_api_key_query) required
-            
             if (!String.IsNullOrEmpty(Configuration.GetApiKeyWithPrefix("test_api_key_query")))
             {
                 queryParams["test_api_key_query"] = Configuration.GetApiKeyWithPrefix("test_api_key_query");
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Category.cs b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Category.cs
index 73cb6dfecfa..f25ee660703 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Category.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Category.cs
@@ -20,9 +20,10 @@ namespace IO.Swagger.Model
         /// <summary>
         /// Initializes a new instance of the <see cref="Category" /> class.
         /// </summary>
-        public Category()
+        public Category(Id = null, Name = null)
         {
             
+            
         }
 
         
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Order.cs b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Order.cs
index 81533a1a586..0e303bcc1cd 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Order.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Order.cs
@@ -20,9 +20,10 @@ namespace IO.Swagger.Model
         /// <summary>
         /// Initializes a new instance of the <see cref="Order" /> class.
         /// </summary>
-        public Order()
+        public Order(Id = null, PetId = null, Quantity = null, ShipDate = null, Status = null, Complete = null)
         {
             
+            
         }
 
         
@@ -30,7 +31,7 @@ namespace IO.Swagger.Model
         /// Gets or Sets Id
         /// </summary>
         [DataMember(Name="id", EmitDefaultValue=false)]
-        public long? Id { get; set; }
+        public long? Id { get;  }
   
         
         /// <summary>
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Pet.cs b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Pet.cs
index 2cb33cbf9e7..f93573b39e5 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Pet.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Pet.cs
@@ -20,8 +20,25 @@ namespace IO.Swagger.Model
         /// <summary>
         /// Initializes a new instance of the <see cref="Pet" /> class.
         /// </summary>
-        public Pet()
+        public Pet(Id = null, Category = null, Name = null, PhotoUrls = null, Tags = null, Status = null)
         {
+            if (Name == null)
+            {
+                throw new InvalidDataException("Name is a required property for Pet and cannot be null");
+            }
+            else
+            {
+                this.Name = Name;
+            }
+            if (PhotoUrls == null)
+            {
+                throw new InvalidDataException("PhotoUrls is a required property for Pet and cannot be null");
+            }
+            else
+            {
+                this.PhotoUrls = PhotoUrls;
+            }
+            
             
         }
 
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Tag.cs b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Tag.cs
index f0fbe098cce..97535433826 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Tag.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/Tag.cs
@@ -20,9 +20,10 @@ namespace IO.Swagger.Model
         /// <summary>
         /// Initializes a new instance of the <see cref="Tag" /> class.
         /// </summary>
-        public Tag()
+        public Tag(Id = null, Name = null)
         {
             
+            
         }
 
         
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/User.cs b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/User.cs
index 89605760978..bda838cf6d6 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/User.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Model/User.cs
@@ -20,9 +20,10 @@ namespace IO.Swagger.Model
         /// <summary>
         /// Initializes a new instance of the <see cref="User" /> class.
         /// </summary>
-        public User()
+        public User(Id = null, Username = null, FirstName = null, LastName = null, Email = null, Password = null, Phone = null, UserStatus = null)
         {
             
+            
         }