diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenModel.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenModel.java
index ccea2ee070e9..438eb1912946 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenModel.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenModel.java
@@ -27,7 +27,7 @@ public class CodegenModel {
     public Set<String> allMandatory;
 
     public Set<String> imports = new TreeSet<String>();
-    public Boolean hasVars, emptyVars, hasMoreModels, hasEnums, isEnum;
+    public Boolean hasVars, emptyVars, hasMoreModels, hasEnums, isEnum, hasRequired;
     public ExternalDocs externalDocs;
 
     public Map<String, Object> vendorExtensions;
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java
index db000e9c63ed..abe9dbea04ef 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java
@@ -2432,6 +2432,7 @@ public class DefaultCodegen {
     private void addVars(CodegenModel m, Map<String, Property> properties, List<String> required,
             Map<String, Property> allProperties, List<String> allRequired) {
 
+        m.hasRequired = false;
         if (properties != null && !properties.isEmpty()) {
             m.hasVars = true;
             m.hasEnums = false;
@@ -2470,6 +2471,7 @@ public class DefaultCodegen {
             } else {
                 final CodegenProperty cp = fromProperty(key, prop);
                 cp.required = mandatory.contains(key) ? true : null;
+                m.hasRequired = Boolean.TRUE.equals(m.hasRequired) || Boolean.TRUE.equals(cp.required);
                 if (cp.isEnum) {
                     // FIXME: if supporting inheritance, when called a second time for allProperties it is possible for
                     // m.hasEnums to be set incorrectly if allProperties has enumerations but properties does not.
diff --git a/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache b/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache
index 2c0f8f681e38..f9b9f7662999 100644
--- a/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache
+++ b/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache
@@ -20,6 +20,11 @@ namespace {{packageName}}.Client
     /// </summary>
     public class ApiClient
     {
+        private JsonSerializerSettings serializerSettings = new JsonSerializerSettings
+        {
+            ConstructorHandling = ConstructorHandling.AllowNonPublicDefaultConstructor
+        };
+
         /// <summary>
         /// Initializes a new instance of the <see cref="ApiClient" /> class
         /// with default configuration and base path ({{basePath}}).
@@ -305,7 +310,7 @@ namespace {{packageName}}.Client
             // at this point, it must be a model (json)
             try
             {
-                return JsonConvert.DeserializeObject(response.Content, type);
+                return JsonConvert.DeserializeObject(response.Content, type, serializerSettings);
             }
             catch (Exception e)
             {
diff --git a/modules/swagger-codegen/src/main/resources/csharp/modelGeneric.mustache b/modules/swagger-codegen/src/main/resources/csharp/modelGeneric.mustache
index 6c5da5e4f56b..ebadaf2046ae 100644
--- a/modules/swagger-codegen/src/main/resources/csharp/modelGeneric.mustache
+++ b/modules/swagger-codegen/src/main/resources/csharp/modelGeneric.mustache
@@ -24,6 +24,13 @@
         public {{{datatypeWithEnum}}}{{#isEnum}}?{{/isEnum}} {{name}} { get; set; }
         {{/isEnum}}
         {{/vars}}
+    {{#hasRequired}}
+        /// <summary>
+        /// Initializes a new instance of the <see cref="{{classname}}" /> class.
+        /// </summary>
+        [JsonConstructorAttribute]
+        protected {{classname}}() { }
+    {{/hasRequired}}
         /// <summary>
         /// Initializes a new instance of the <see cref="{{classname}}" /> class.
         /// </summary>