diff --git a/modules/swagger-codegen/src/main/java/com/wordnik/swagger/codegen/languages/CSharpClientCodegen.java b/modules/swagger-codegen/src/main/java/com/wordnik/swagger/codegen/languages/CSharpClientCodegen.java
index 9de427058a1..ceb4849bd2a 100644
--- a/modules/swagger-codegen/src/main/java/com/wordnik/swagger/codegen/languages/CSharpClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/com/wordnik/swagger/codegen/languages/CSharpClientCodegen.java
@@ -41,9 +41,11 @@ public class CSharpClientCodegen extends DefaultCodegen implements CodegenConfig
 
     additionalProperties.put("invokerPackage", invokerPackage);
 
-    supportingFiles.add(new SupportingFile("apiInvoker.mustache", 
-      (sourceFolder + File.separator + invokerPackage).replace(".", java.io.File.separator), "ApiInvoker.cs"));
-    supportingFiles.add(new SupportingFile("apiException.mustache", 
+    supportingFiles.add(new SupportingFile("Configuration.mustache", 
+      (sourceFolder + File.separator + invokerPackage).replace(".", java.io.File.separator), "Configuration.cs"));
+    supportingFiles.add(new SupportingFile("ApiClient.mustache", 
+      (sourceFolder + File.separator + invokerPackage).replace(".", java.io.File.separator), "ApiClient.cs"));
+    supportingFiles.add(new SupportingFile("ApiException.mustache", 
       (sourceFolder + File.separator + invokerPackage).replace(".", java.io.File.separator), "ApiException.cs"));
     supportingFiles.add(new SupportingFile("Newtonsoft.Json.dll", "bin", "Newtonsoft.Json.dll"));
     supportingFiles.add(new SupportingFile("compile.mustache", "", "compile.bat"));
diff --git a/modules/swagger-codegen/src/main/resources/csharp/apiInvoker.mustache b/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache
similarity index 92%
rename from modules/swagger-codegen/src/main/resources/csharp/apiInvoker.mustache
rename to modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache
index 01406a8add0..469d5e94c37 100644
--- a/modules/swagger-codegen/src/main/resources/csharp/apiInvoker.mustache
+++ b/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache
@@ -8,13 +8,15 @@ using Newtonsoft.Json;
 using RestSharp;
 
 namespace {{invokerPackage}} {
-  public class ApiInvoker {
-    public ApiInvoker() {
+  public class ApiClient {
+    public ApiClient() {
       this.basePath = "{{basePath}}";
+      this.restClient = new RestClient(this.basePath);
     }
 
-    public ApiInvoker(String basePath) {
+    public ApiClient(String basePath) {
       this.basePath = basePath;
+      this.restClient = new RestClient(this.basePath);
     }
 
     public string basePath { get; set; }
@@ -43,10 +45,10 @@ namespace {{invokerPackage}} {
         request.AddParameter(param.Key, param.Value);
 
       // add file parameter, if any
-      foreach(KeyValuePair<string, string> param in FormParams)
+      foreach(KeyValuePair<string, string> param in FileParams)
         request.AddFile(param.Key, param.Value);
 
-      if (PostBody == null) {
+      if (PostBody != null) {
         request.AddParameter("application/json", PostBody, ParameterType.RequestBody); // http body (model) parameter
       }
 
diff --git a/modules/swagger-codegen/src/main/resources/csharp/Configuration.mustache b/modules/swagger-codegen/src/main/resources/csharp/Configuration.mustache
new file mode 100644
index 00000000000..41c371be487
--- /dev/null
+++ b/modules/swagger-codegen/src/main/resources/csharp/Configuration.mustache
@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Net;
+using System.Text;
+using {{invokerPackage}};
+
+namespace {{invokerPackage}} {
+  public class Configuration{
+    public static ApiClient apiClient = new ApiClient();
+
+  }
+}
diff --git a/modules/swagger-codegen/src/main/resources/csharp/api.mustache b/modules/swagger-codegen/src/main/resources/csharp/api.mustache
index ee3f326c746..c78b7461c7e 100644
--- a/modules/swagger-codegen/src/main/resources/csharp/api.mustache
+++ b/modules/swagger-codegen/src/main/resources/csharp/api.mustache
@@ -10,12 +10,25 @@ namespace {{package}} {
   {{#operations}}
   public class {{classname}} {
     string basePath;
-    public ApiInvoker apiClient {get; set;}
+    public ApiClient apiClient {get; set;}
 
     public {{classname}}(String basePath = "{{basePath}}")
     {
       this.basePath = basePath;
-      this.apiClient = new ApiInvoker(basePath);
+      this.apiClient = new ApiClient(basePath);
+    }
+
+    /// <summary>
+    /// Create a new object 
+    /// </summary>
+    /// <param name="apiClient"> an instance of ApiClient
+    /// <returns></returns>
+    public {{classname}}(ApiClient apiClient = null) {
+      if (apiClient == null) { // use the default one in Configuration
+        this.apiClient = Configuration.apiClient; 
+      } else {
+        this.apiClient = apiClient;
+      }
     }
 
     /// <summary>
@@ -36,7 +49,6 @@ namespace {{package}} {
     }
 
     {{#operation}}
-    
     /// <summary>
     /// {{summary}} {{notes}}
     /// </summary>
@@ -71,7 +83,7 @@ namespace {{package}} {
       {{/bodyParam}}
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("{{path}}", Method.{{httpMethod}}, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.{{httpMethod}}, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling {{nickname}}: " + response.Content);
diff --git a/samples/client/petstore/csharp/src/main/csharp/io/swagger/Api/PetApi.cs b/samples/client/petstore/csharp/src/main/csharp/io/swagger/Api/PetApi.cs
index 054cb1bc204..4c7cd680bed 100644
--- a/samples/client/petstore/csharp/src/main/csharp/io/swagger/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/src/main/csharp/io/swagger/Api/PetApi.cs
@@ -8,12 +8,25 @@ namespace IO.Swagger.Api {
   
   public class PetApi {
     string basePath;
-    public ApiInvoker apiClient {get; set;}
+    public ApiClient apiClient {get; set;}
 
     public PetApi(String basePath = "http://petstore.swagger.io/v2")
     {
       this.basePath = basePath;
-      this.apiClient = new ApiInvoker(basePath);
+      this.apiClient = new ApiClient(basePath);
+    }
+
+    /// <summary>
+    /// Create a new object 
+    /// </summary>
+    /// <param name="apiClient"> an instance of ApiClient
+    /// <returns></returns>
+    public PetApi(ApiClient apiClient = null) {
+      if (apiClient == null) { // use the default one in Configuration
+        this.apiClient = Configuration.apiClient; 
+      } else {
+        this.apiClient = apiClient;
+      }
     }
 
     /// <summary>
@@ -34,7 +47,6 @@ namespace IO.Swagger.Api {
     }
 
     
-    
     /// <summary>
     /// Update an existing pet 
     /// </summary>
@@ -61,7 +73,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/pet", Method.PUT, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.PUT, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling UpdatePet: " + response.Content);
@@ -70,7 +82,6 @@ namespace IO.Swagger.Api {
       return;
     }
     
-    
     /// <summary>
     /// Add a new pet to the store 
     /// </summary>
@@ -97,7 +108,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/pet", Method.POST, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.POST, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling AddPet: " + response.Content);
@@ -106,7 +117,6 @@ namespace IO.Swagger.Api {
       return;
     }
     
-    
     /// <summary>
     /// Finds Pets by status Multiple status values can be provided with comma seperated strings
     /// </summary>
@@ -133,7 +143,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/pet/findByStatus", Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling FindPetsByStatus: " + response.Content);
@@ -141,7 +151,6 @@ namespace IO.Swagger.Api {
       return (List<Pet>) apiClient.Deserialize(response.Content, typeof(List<Pet>));
     }
     
-    
     /// <summary>
     /// Finds Pets by tags Muliple tags can be provided with comma seperated strings. Use tag1, tag2, tag3 for testing.
     /// </summary>
@@ -168,7 +177,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/pet/findByTags", Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling FindPetsByTags: " + response.Content);
@@ -176,7 +185,6 @@ namespace IO.Swagger.Api {
       return (List<Pet>) apiClient.Deserialize(response.Content, typeof(List<Pet>));
     }
     
-    
     /// <summary>
     /// Find pet by ID Returns a pet when ID &lt; 10.  ID &gt; 10 or nonintegers will simulate API error conditions
     /// </summary>
@@ -206,7 +214,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/pet/{petId}", Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling GetPetById: " + response.Content);
@@ -214,7 +222,6 @@ namespace IO.Swagger.Api {
       return (Pet) apiClient.Deserialize(response.Content, typeof(Pet));
     }
     
-    
     /// <summary>
     /// Updates a pet in the store with form data 
     /// </summary>
@@ -248,7 +255,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/pet/{petId}", Method.POST, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.POST, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling UpdatePetWithForm: " + response.Content);
@@ -257,7 +264,6 @@ namespace IO.Swagger.Api {
       return;
     }
     
-    
     /// <summary>
     /// Deletes a pet 
     /// </summary>
@@ -289,7 +295,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/pet/{petId}", Method.DELETE, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.DELETE, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling DeletePet: " + response.Content);
@@ -298,7 +304,6 @@ namespace IO.Swagger.Api {
       return;
     }
     
-    
     /// <summary>
     /// uploads an image 
     /// </summary>
@@ -332,7 +337,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/pet/{petId}/uploadImage", Method.POST, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.POST, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling UploadFile: " + response.Content);
diff --git a/samples/client/petstore/csharp/src/main/csharp/io/swagger/Api/StoreApi.cs b/samples/client/petstore/csharp/src/main/csharp/io/swagger/Api/StoreApi.cs
index 9d10a095c44..9fa4a528a07 100644
--- a/samples/client/petstore/csharp/src/main/csharp/io/swagger/Api/StoreApi.cs
+++ b/samples/client/petstore/csharp/src/main/csharp/io/swagger/Api/StoreApi.cs
@@ -8,12 +8,25 @@ namespace IO.Swagger.Api {
   
   public class StoreApi {
     string basePath;
-    public ApiInvoker apiClient {get; set;}
+    public ApiClient apiClient {get; set;}
 
     public StoreApi(String basePath = "http://petstore.swagger.io/v2")
     {
       this.basePath = basePath;
-      this.apiClient = new ApiInvoker(basePath);
+      this.apiClient = new ApiClient(basePath);
+    }
+
+    /// <summary>
+    /// Create a new object 
+    /// </summary>
+    /// <param name="apiClient"> an instance of ApiClient
+    /// <returns></returns>
+    public StoreApi(ApiClient apiClient = null) {
+      if (apiClient == null) { // use the default one in Configuration
+        this.apiClient = Configuration.apiClient; 
+      } else {
+        this.apiClient = apiClient;
+      }
     }
 
     /// <summary>
@@ -34,7 +47,6 @@ namespace IO.Swagger.Api {
     }
 
     
-    
     /// <summary>
     /// Returns pet inventories by status Returns a map of status codes to quantities
     /// </summary>
@@ -59,7 +71,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/store/inventory", Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling GetInventory: " + response.Content);
@@ -67,7 +79,6 @@ namespace IO.Swagger.Api {
       return (Dictionary<String, int?>) apiClient.Deserialize(response.Content, typeof(Dictionary<String, int?>));
     }
     
-    
     /// <summary>
     /// Place an order for a pet 
     /// </summary>
@@ -94,7 +105,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/store/order", Method.POST, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.POST, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling PlaceOrder: " + response.Content);
@@ -102,7 +113,6 @@ namespace IO.Swagger.Api {
       return (Order) apiClient.Deserialize(response.Content, typeof(Order));
     }
     
-    
     /// <summary>
     /// Find purchase order by ID For valid response try integer IDs with value &lt;= 5 or &gt; 10. Other values will generated exceptions
     /// </summary>
@@ -132,7 +142,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/store/order/{orderId}", Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling GetOrderById: " + response.Content);
@@ -140,7 +150,6 @@ namespace IO.Swagger.Api {
       return (Order) apiClient.Deserialize(response.Content, typeof(Order));
     }
     
-    
     /// <summary>
     /// Delete purchase order by ID For valid response try integer IDs with value &lt; 1000. Anything above 1000 or nonintegers will generate API errors
     /// </summary>
@@ -170,7 +179,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/store/order/{orderId}", Method.DELETE, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.DELETE, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling DeleteOrder: " + response.Content);
diff --git a/samples/client/petstore/csharp/src/main/csharp/io/swagger/Api/UserApi.cs b/samples/client/petstore/csharp/src/main/csharp/io/swagger/Api/UserApi.cs
index c225f45496d..0d6707d88cf 100644
--- a/samples/client/petstore/csharp/src/main/csharp/io/swagger/Api/UserApi.cs
+++ b/samples/client/petstore/csharp/src/main/csharp/io/swagger/Api/UserApi.cs
@@ -8,12 +8,25 @@ namespace IO.Swagger.Api {
   
   public class UserApi {
     string basePath;
-    public ApiInvoker apiClient {get; set;}
+    public ApiClient apiClient {get; set;}
 
     public UserApi(String basePath = "http://petstore.swagger.io/v2")
     {
       this.basePath = basePath;
-      this.apiClient = new ApiInvoker(basePath);
+      this.apiClient = new ApiClient(basePath);
+    }
+
+    /// <summary>
+    /// Create a new object 
+    /// </summary>
+    /// <param name="apiClient"> an instance of ApiClient
+    /// <returns></returns>
+    public UserApi(ApiClient apiClient = null) {
+      if (apiClient == null) { // use the default one in Configuration
+        this.apiClient = Configuration.apiClient; 
+      } else {
+        this.apiClient = apiClient;
+      }
     }
 
     /// <summary>
@@ -34,7 +47,6 @@ namespace IO.Swagger.Api {
     }
 
     
-    
     /// <summary>
     /// Create user This can only be done by the logged in user.
     /// </summary>
@@ -61,7 +73,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/user", Method.POST, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.POST, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling CreateUser: " + response.Content);
@@ -70,7 +82,6 @@ namespace IO.Swagger.Api {
       return;
     }
     
-    
     /// <summary>
     /// Creates list of users with given input array 
     /// </summary>
@@ -97,7 +108,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/user/createWithArray", Method.POST, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.POST, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling CreateUsersWithArrayInput: " + response.Content);
@@ -106,7 +117,6 @@ namespace IO.Swagger.Api {
       return;
     }
     
-    
     /// <summary>
     /// Creates list of users with given input array 
     /// </summary>
@@ -133,7 +143,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/user/createWithList", Method.POST, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.POST, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling CreateUsersWithListInput: " + response.Content);
@@ -142,7 +152,6 @@ namespace IO.Swagger.Api {
       return;
     }
     
-    
     /// <summary>
     /// Logs user into the system 
     /// </summary>
@@ -171,7 +180,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/user/login", Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling LoginUser: " + response.Content);
@@ -179,7 +188,6 @@ namespace IO.Swagger.Api {
       return (string) apiClient.Deserialize(response.Content, typeof(string));
     }
     
-    
     /// <summary>
     /// Logs out current logged in user session 
     /// </summary>
@@ -204,7 +212,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/user/logout", Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling LogoutUser: " + response.Content);
@@ -213,7 +221,6 @@ namespace IO.Swagger.Api {
       return;
     }
     
-    
     /// <summary>
     /// Get user by user name 
     /// </summary>
@@ -243,7 +250,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/user/{username}", Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.GET, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling GetUserByName: " + response.Content);
@@ -251,7 +258,6 @@ namespace IO.Swagger.Api {
       return (User) apiClient.Deserialize(response.Content, typeof(User));
     }
     
-    
     /// <summary>
     /// Updated user This can only be done by the logged in user.
     /// </summary>
@@ -283,7 +289,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/user/{username}", Method.PUT, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.PUT, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling UpdateUser: " + response.Content);
@@ -292,7 +298,6 @@ namespace IO.Swagger.Api {
       return;
     }
     
-    
     /// <summary>
     /// Delete user This can only be done by the logged in user.
     /// </summary>
@@ -322,7 +327,7 @@ namespace IO.Swagger.Api {
       
 
       // make the HTTP request
-      IRestResponse response = (IRestResponse) apiClient.CallApi("/user/{username}", Method.DELETE, queryParams, postBody, headerParams, formParams, fileParams);
+      IRestResponse response = (IRestResponse) apiClient.CallApi(path, Method.DELETE, queryParams, postBody, headerParams, formParams, fileParams);
 
       if (((int)response.StatusCode) >= 400) {
         throw new ApiException ((int)response.StatusCode, "Error calling DeleteUser: " + response.Content);
diff --git a/samples/client/petstore/csharp/src/main/csharp/io/swagger/client/ApiInvoker.cs b/samples/client/petstore/csharp/src/main/csharp/io/swagger/client/ApiClient.cs
similarity index 92%
rename from samples/client/petstore/csharp/src/main/csharp/io/swagger/client/ApiInvoker.cs
rename to samples/client/petstore/csharp/src/main/csharp/io/swagger/client/ApiClient.cs
index ce5cf0263eb..2a48e4b3075 100644
--- a/samples/client/petstore/csharp/src/main/csharp/io/swagger/client/ApiInvoker.cs
+++ b/samples/client/petstore/csharp/src/main/csharp/io/swagger/client/ApiClient.cs
@@ -8,13 +8,15 @@ using Newtonsoft.Json;
 using RestSharp;
 
 namespace IO.Swagger.Client {
-  public class ApiInvoker {
-    public ApiInvoker() {
+  public class ApiClient {
+    public ApiClient() {
       this.basePath = "http://petstore.swagger.io/v2";
+      this.restClient = new RestClient(this.basePath);
     }
 
-    public ApiInvoker(String basePath) {
+    public ApiClient(String basePath) {
       this.basePath = basePath;
+      this.restClient = new RestClient(this.basePath);
     }
 
     public string basePath { get; set; }
@@ -43,10 +45,10 @@ namespace IO.Swagger.Client {
         request.AddParameter(param.Key, param.Value);
 
       // add file parameter, if any
-      foreach(KeyValuePair<string, string> param in FormParams)
+      foreach(KeyValuePair<string, string> param in FileParams)
         request.AddFile(param.Key, param.Value);
 
-      if (PostBody == null) {
+      if (PostBody != null) {
         request.AddParameter("application/json", PostBody, ParameterType.RequestBody); // http body (model) parameter
       }
 
diff --git a/samples/client/petstore/csharp/src/main/csharp/io/swagger/client/Configuration.cs b/samples/client/petstore/csharp/src/main/csharp/io/swagger/client/Configuration.cs
new file mode 100644
index 00000000000..815bb027c8f
--- /dev/null
+++ b/samples/client/petstore/csharp/src/main/csharp/io/swagger/client/Configuration.cs
@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Net;
+using System.Text;
+using IO.Swagger.Client;
+
+namespace IO.Swagger.Client {
+  public class Configuration{
+    public static ApiClient apiClient = new ApiClient();
+
+  }
+}