[csharp-netcore] Nrt (nullableReferenceTypes) refactor (#11452)

* refactor nrt annotation

* enable nrt by default in .net6.0+

* use shorter nrt annotation

* build samples

* removed debugging lines

docs/generators/csharp-netcore.md

@@ -30,7 +30,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name| |PascalCase|
 |netCoreProjectFile|Use the new format (.NET Core) for .NET project files (.csproj).| |false|
 |nonPublicApi|Generates code with reduced access modifiers; allows embedding elsewhere without exposing non-public API calls to consumers.| |false|
-|nullableReferenceTypes|Use nullable annotations in the project. Only supported on C# 8 / ASP.NET Core 3.1 or newer.| |false|
+|nullableReferenceTypes|Use nullable annotations in the project. Only supported on C# 8 / ASP.NET Core 3.1 or newer. Starting in .NET 6.0 the default is true.| |false|
 |optionalAssemblyInfo|Generate AssemblyInfo.cs.| |true|
 |optionalEmitDefaultValues|Set DataMember's EmitDefaultValue.| |false|
 |optionalMethodArgument|C# Optional method argument, e.g. void square(int x=10) (.net 4.0+ only).| |true|

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractCSharpCodegen.java

@@ -369,8 +369,6 @@ public abstract class AbstractCSharpCodegen extends DefaultCodegen implements Co
 
         if (additionalProperties.containsKey(CodegenConstants.NULLABLE_REFERENCE_TYPES)) {
             setNullableReferenceTypes(convertPropertyToBooleanAndWriteBack(CodegenConstants.NULLABLE_REFERENCE_TYPES));
-        } else {
-            additionalProperties.put(CodegenConstants.NULLABLE_REFERENCE_TYPES, nullReferenceTypesFlag);
         }
 
         if (additionalProperties.containsKey(CodegenConstants.INTERFACE_PREFIX)) {
@@ -1165,8 +1163,17 @@ public abstract class AbstractCSharpCodegen extends DefaultCodegen implements Co
 
     public void setNullableReferenceTypes(final Boolean nullReferenceTypesFlag){
         this.nullReferenceTypesFlag = nullReferenceTypesFlag;
-        if (nullReferenceTypesFlag == true){
+        additionalProperties.put("nullableReferenceTypes", nullReferenceTypesFlag);
+        additionalProperties.put("nrt", nullReferenceTypesFlag);
+
+        if (nullReferenceTypesFlag){
             this.nullableType.add("string");
+            additionalProperties.put("nrt?", "?");
+            additionalProperties.put("nrt!", "!");
+        } else {
+            this.nullableType.remove("string");
+            additionalProperties.remove("nrt?");
+            additionalProperties.remove("nrt!");
         }
     }
 

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CSharpNetCoreClientCodegen.java

@@ -240,7 +240,7 @@ public class CSharpNetCoreClientCodegen extends AbstractCSharpCodegen {
 
         // CLI Switches
         addSwitch(CodegenConstants.NULLABLE_REFERENCE_TYPES,
-                CodegenConstants.NULLABLE_REFERENCE_TYPES_DESC,
+                CodegenConstants.NULLABLE_REFERENCE_TYPES_DESC + " Starting in .NET 6.0 the default is true.",
                 this.nullReferenceTypesFlag);
 
         addSwitch(CodegenConstants.HIDE_GENERATION_TIMESTAMP,
@@ -655,11 +655,17 @@ public class CSharpNetCoreClientCodegen extends AbstractCSharpCodegen {
 
         if (!netStandard) {
             setNetCoreProjectFileFlag(true);
-        }
 
-        if (additionalProperties.containsKey(CodegenConstants.GENERATE_PROPERTY_CHANGED)) {
+            if (!additionalProperties.containsKey(CodegenConstants.NULLABLE_REFERENCE_TYPES) && !strategies.stream().anyMatch(s -> 
-            LOGGER.warn("{} is not supported in the .NET Standard generator.", CodegenConstants.GENERATE_PROPERTY_CHANGED);
+                        s.equals(FrameworkStrategy.NETCOREAPP_2_0) ||
-            additionalProperties.remove(CodegenConstants.GENERATE_PROPERTY_CHANGED);
+                        s.equals(FrameworkStrategy.NETCOREAPP_2_1) ||
+                        s.equals(FrameworkStrategy.NETCOREAPP_3_0) ||
+                        s.equals(FrameworkStrategy.NETCOREAPP_3_1) ||
+                        s.equals(FrameworkStrategy.NET_5_0) ||
+                        s.equals(FrameworkStrategy.NETFRAMEWORK_4_7))) {
+                // starting in .net 6.0, NRT is enabled by default. If not specified, lets enable NRT to match the framework's default
+                setNullableReferenceTypes(true);
+            }
         }
 
         final AtomicReference<Boolean> excludeTests = new AtomicReference<>();

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/ApiException.mustache

@@ -1,6 +1,6 @@
 // <auto-generated>
 {{>partial_header}}
-{{#nullableReferenceTypes}}#nullable enable{{/nullableReferenceTypes}}
+{{#nrt}}#nullable enable{{/nrt}}
 
 using System;
 
@@ -14,7 +14,7 @@ namespace {{packageName}}.Client
         /// <summary>
         /// The reason the api request failed
         /// </summary>
-        public string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} ReasonPhrase { get; }
+        public string{{nrt?}} ReasonPhrase { get; }
 
         /// <summary>
         /// The HttpStatusCode
@@ -32,7 +32,7 @@ namespace {{packageName}}.Client
         /// <param name="reasonPhrase"></param>
         /// <param name="statusCode"></param>
         /// <param name="rawContent"></param>
-        public ApiException(string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} reasonPhrase, System.Net.HttpStatusCode statusCode, string rawContent) : base(reasonPhrase ?? rawContent)
+        public ApiException(string{{nrt?}} reasonPhrase, System.Net.HttpStatusCode statusCode, string rawContent) : base(reasonPhrase ?? rawContent)
         {
             ReasonPhrase = reasonPhrase;
 

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/ApiKeyToken.mustache

@@ -1,6 +1,6 @@
 // <auto-generated>
 {{partial_header}}
-{{#nullableReferenceTypes}}#nullable enable{{/nullableReferenceTypes}}
+{{#nrt}}#nullable enable{{/nrt}}
 
 using System;
 
@@ -53,7 +53,7 @@ namespace {{packageName}}.Client
         /// <param name="parameterName"></param>
         public virtual void UseInQuery(System.Net.Http.HttpRequestMessage request, UriBuilder uriBuilder, System.Collections.Specialized.NameValueCollection parseQueryString, string parameterName)
         {
-            parseQueryString[parameterName] = Uri.EscapeDataString(_raw).ToString(){{#nullableReferenceTypes}}!{{/nullableReferenceTypes}};
+            parseQueryString[parameterName] = Uri.EscapeDataString(_raw).ToString(){{nrt!}};
         }
     }
 }

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/ApiResponse`1.mustache

@@ -1,6 +1,6 @@
 // <auto-generated>
 {{>partial_header}}
-{{#nullableReferenceTypes}}#nullable enable{{/nullableReferenceTypes}}
+{{#nrt}}#nullable enable{{/nrt}}
 
 using System;
 using System.Collections.Generic;
@@ -42,7 +42,7 @@ namespace {{packageName}}.Client
         /// The deserialized content
         /// </summary>
         {{! .net 3.1 does not support unconstrained nullable T }}
-        public T{{#nullableReferenceTypes}}{{^netcoreapp3.1}}?{{/netcoreapp3.1}}{{/nullableReferenceTypes}} Content { get; set; }
+        public T{{#nrt}}{{^netcoreapp3.1}}?{{/netcoreapp3.1}}{{/nrt}} Content { get; set; }
 
         /// <summary>
         /// Gets or sets the status code (HTTP status code)
@@ -71,7 +71,7 @@ namespace {{packageName}}.Client
         /// <summary>
         /// The reason phrase contained in the api response
         /// </summary>
-        public string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} ReasonPhrase { get; }
+        public string{{nrt?}} ReasonPhrase { get; }
 
         /// <summary>
         /// The headers contained in the api response

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/BasicToken.mustache

@@ -1,6 +1,6 @@
 // <auto-generated>
 {{partial_header}}
-{{#nullableReferenceTypes}}#nullable enable{{/nullableReferenceTypes}}
+{{#nrt}}#nullable enable{{/nrt}}
 
 using System;
 using System.Linq;

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/BearerToken.mustache

@@ -1,6 +1,6 @@
 // <auto-generated>
 {{partial_header}}
-{{#nullableReferenceTypes}}#nullable enable{{/nullableReferenceTypes}}
+{{#nrt}}#nullable enable{{/nrt}}
 
 using System;
 using System.Linq;

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/ClientUtils.mustache

@@ -81,7 +81,7 @@ namespace {{packageName}}.Client
         /// <param name="obj">The parameter (header, path, query, form).</param>
         /// <param name="format">The DateTime serialization format.</param>
         /// <returns>Formatted string.</returns>
-        public static string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} ParameterToString(object obj, string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} format = ISO8601_DATETIME_FORMAT)
+        public static string{{nrt?}} ParameterToString(object obj, string{{nrt?}} format = ISO8601_DATETIME_FORMAT)
         {
             if (obj is DateTime dateTime)
                 // Return a formatted date string - Can be customized with Configuration.DateTimeFormat

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/HostConfiguration.mustache

@@ -35,7 +35,7 @@ namespace {{packageName}}.Client
         /// <returns></returns>
         public HostConfiguration Add{{apiName}}HttpClients<{{#apiInfo}}{{#apis}}T{{classname}}{{^-last}}, {{/-last}}{{/apis}}>
         (
-            Action<HttpClient>{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} client = null, Action<IHttpClientBuilder>{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} builder = null){{#apis}}
+            Action<HttpClient>{{nrt?}} client = null, Action<IHttpClientBuilder>{{nrt?}} builder = null){{#apis}}
             where T{{classname}} : class, {{interfacePrefix}}{{classname}}{{/apis}}
         {
             if (client == null)
@@ -61,7 +61,7 @@ namespace {{packageName}}.Client
         /// <param name="builder"></param>
         /// <returns></returns>
         public HostConfiguration Add{{apiName}}HttpClients(
-            Action<HttpClient>{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} client = null, Action<IHttpClientBuilder>{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} builder = null)
+            Action<HttpClient>{{nrt?}} client = null, Action<IHttpClientBuilder>{{nrt?}} builder = null)
         {
             Add{{apiName}}HttpClients<{{#apiInfo}}{{#apis}}{{classname}}{{^-last}}, {{/-last}}{{/apis}}{{/apiInfo}}>(client, builder);
 

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/HttpSigningConfiguration.mustache

@@ -1,6 +1,6 @@
 // <auto-generated>
 {{>partial_header}}
-{{#nullableReferenceTypes}}#nullable enable{{/nullableReferenceTypes}}
+{{#nrt}}#nullable enable{{/nrt}}
 
 using System;
 using System.Collections.Generic;
@@ -22,7 +22,7 @@ namespace {{packageName}}.Client
         /// <summary>
         /// Create an instance
         /// </summary>
-        public HttpSigningConfiguration(string keyId, string keyFilePath, SecureString{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} keyPassPhrase, List<string> httpSigningHeader, HashAlgorithmName hashAlgorithm, string signingAlgorithm, int signatureValidityPeriod)
+        public HttpSigningConfiguration(string keyId, string keyFilePath, SecureString{{nrt?}} keyPassPhrase, List<string> httpSigningHeader, HashAlgorithmName hashAlgorithm, string signingAlgorithm, int signatureValidityPeriod)
         {
             KeyId = keyId;
             KeyFilePath = keyFilePath;
@@ -48,7 +48,7 @@ namespace {{packageName}}.Client
         /// <summary>
         /// Gets the key pass phrase for password protected key
         /// </summary>
-        public SecureString{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} KeyPassPhrase { get; set; }
+        public SecureString{{nrt?}} KeyPassPhrase { get; set; }
 
         /// <summary>
         /// Gets the HTTP signing header
@@ -118,7 +118,7 @@ namespace {{packageName}}.Client
             //Hash table to store singed headers
             var HttpSignedRequestHeader = new Dictionary<string, string>();
             
-            var httpSignatureHeader = new Dictionary<string, string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}>();
+            var httpSignatureHeader = new Dictionary<string, string{{nrt?}}>();
 
             if (HttpSigningHeader.Count == 0)
                 HttpSigningHeader.Add("(created)");
@@ -191,7 +191,7 @@ namespace {{packageName}}.Client
             //Concatinate headers value separated by new line
             var headerValuesString = string.Join("\n", headerValuesList);
             var signatureStringHash = GetStringHash(HashAlgorithm.ToString(), headerValuesString);
-            string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} headerSignatureStr = null;
+            string{{nrt?}} headerSignatureStr = null;
             var keyType = GetKeyType(KeyFilePath);
 
             if (keyType == PrivateKeyType.RSA)
@@ -241,7 +241,7 @@ namespace {{packageName}}.Client
             if (KeyPassPhrase == null)
                 throw new NullReferenceException($"{ nameof(KeyPassPhrase) } was null.");
 
-            RSA{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} rsa = GetRSAProviderFromPemFile(KeyFilePath, KeyPassPhrase);
+            RSA{{nrt?}} rsa = GetRSAProviderFromPemFile(KeyFilePath, KeyPassPhrase);
             
             if (rsa == null)
                 return string.Empty;
@@ -363,12 +363,12 @@ namespace {{packageName}}.Client
             return derBytes.ToArray();
         }
 
-        private  RSACryptoServiceProvider{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} GetRSAProviderFromPemFile(String pemfile, SecureString{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} keyPassPharse = null)
+        private  RSACryptoServiceProvider{{nrt?}} GetRSAProviderFromPemFile(String pemfile, SecureString{{nrt?}} keyPassPharse = null)
         {
             const String pempubheader = "-----BEGIN PUBLIC KEY-----";
             const String pempubfooter = "-----END PUBLIC KEY-----";
             bool isPrivateKeyFile = true;
-            byte[]{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} pemkey = null;
+            byte[]{{nrt?}} pemkey = null;
 
             if (!File.Exists(pemfile))
                 throw new Exception("private key file does not exist.");
@@ -390,7 +390,7 @@ namespace {{packageName}}.Client
             return null;
         }
 
-        private byte[]{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} ConvertPrivateKeyToBytes(String instr, SecureString{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} keyPassPharse = null)
+        private byte[]{{nrt?}} ConvertPrivateKeyToBytes(String instr, SecureString{{nrt?}} keyPassPharse = null)
         {
             const String pemprivheader = "-----BEGIN RSA PRIVATE KEY-----";
             const String pemprivfooter = "-----END RSA PRIVATE KEY-----";
@@ -415,10 +415,10 @@ namespace {{packageName}}.Client
                 StringReader str = new StringReader(pvkstr);
 
                 //-------- read PEM encryption info. lines and extract salt -----
-                if (!str.ReadLine(){{#nullableReferenceTypes}}!{{/nullableReferenceTypes}}.StartsWith("Proc-Type: 4,ENCRYPTED"))  // TODO: what do we do here if ReadLine is null?
+                if (!str.ReadLine(){{nrt!}}.StartsWith("Proc-Type: 4,ENCRYPTED"))  // TODO: what do we do here if ReadLine is null?
                     return null;
                 
-                String saltline = str.ReadLine(){{#nullableReferenceTypes}}!{{/nullableReferenceTypes}};  // TODO: what do we do here if ReadLine is null?
+                String saltline = str.ReadLine(){{nrt!}};  // TODO: what do we do here if ReadLine is null?
                 if (!saltline.StartsWith("DEK-Info: DES-EDE3-CBC,"))
                     return null;
                 
@@ -443,18 +443,18 @@ namespace {{packageName}}.Client
                 }
 
                 // TODO: what do we do here if keyPassPharse is null?
-                byte[] deskey = GetEncryptedKey(salt, keyPassPharse{{#nullableReferenceTypes}}!{{/nullableReferenceTypes}}, 1, 2);    // count=1 (for OpenSSL implementation); 2 iterations to get at least 24 bytes
+                byte[] deskey = GetEncryptedKey(salt, keyPassPharse{{nrt!}}, 1, 2);    // count=1 (for OpenSSL implementation); 2 iterations to get at least 24 bytes
                 if (deskey == null)
                     return null;
 
                 //------ Decrypt the encrypted 3des-encrypted RSA private key ------
-                byte[]{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} rsakey = DecryptKey(binkey, deskey, salt); //OpenSSL uses salt value in PEM header also as 3DES IV
+                byte[]{{nrt?}} rsakey = DecryptKey(binkey, deskey, salt); //OpenSSL uses salt value in PEM header also as 3DES IV
 
                 return rsakey;
             }
         }
 
-        private RSACryptoServiceProvider{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} DecodeRSAPrivateKey(byte[] privkey)
+        private RSACryptoServiceProvider{{nrt?}} DecodeRSAPrivateKey(byte[] privkey)
         {
             byte[] MODULUS, E, D, P, Q, DP, DQ, IQ;
 
@@ -583,7 +583,7 @@ namespace {{packageName}}.Client
 
             // ---- do multi-hashing and concatenate results  D1, D2 ...  into keymaterial bytes ----
             MD5 md5 = new MD5CryptoServiceProvider();
-            byte[]{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} result = null;
+            byte[]{{nrt?}} result = null;
             byte[] hashtarget = new byte[HASHLENGTH + data00.Length];   //fixed length initial hashtarget
 
             for (int j = 0; j < miter; j++)
@@ -593,7 +593,7 @@ namespace {{packageName}}.Client
                     result = data00;    //initialize
                 else
                 {
-                    Array.Copy(result{{#nullableReferenceTypes}}!{{/nullableReferenceTypes}}, hashtarget, result{{#nullableReferenceTypes}}!{{/nullableReferenceTypes}}.Length); // TODO: what do we do if result is null here?
+                    Array.Copy(result{{nrt!}}, hashtarget, result{{nrt!}}.Length); // TODO: what do we do if result is null here?
                     Array.Copy(data00, 0, hashtarget, result.Length, data00.Length);
                     result = hashtarget;
                 }
@@ -608,13 +608,13 @@ namespace {{packageName}}.Client
 
             Array.Clear(psbytes, 0, psbytes.Length);
             Array.Clear(data00, 0, data00.Length);
-            Array.Clear(result{{#nullableReferenceTypes}}!{{/nullableReferenceTypes}}, 0, result{{#nullableReferenceTypes}}!{{/nullableReferenceTypes}}.Length); // TODO: what do we do if result is null here?
+            Array.Clear(result{{nrt!}}, 0, result{{nrt!}}.Length); // TODO: what do we do if result is null here?
             Array.Clear(hashtarget, 0, hashtarget.Length);
             Array.Clear(keymaterial, 0, keymaterial.Length);
             return deskey;
         }
 
-        private byte[]{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} DecryptKey(byte[] cipherData, byte[] desKey, byte[] IV)
+        private byte[]{{nrt?}} DecryptKey(byte[] cipherData, byte[] desKey, byte[] IV)
         {
             MemoryStream memst = new MemoryStream();
             TripleDES alg = TripleDES.Create();

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/HttpSigningToken.mustache

@@ -1,6 +1,6 @@
 // <auto-generated>
 {{partial_header}}
-{{#nullableReferenceTypes}}#nullable enable{{/nullableReferenceTypes}}
+{{#nrt}}#nullable enable{{/nrt}}
 
 using System;
 using System.Linq;

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/IApi.mustache

@@ -16,6 +16,6 @@ namespace {{packageName}}.Client
         /// An event to track the health of the server. 
         /// If you store these event args, be sure to purge old event args to prevent a memory leak.
         /// </summary>
-        event ClientUtils.EventHandler<ApiResponseEventArgs>{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} ApiResponded;
+        event ClientUtils.EventHandler<ApiResponseEventArgs>{{nrt?}} ApiResponded;
     }
 }

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/OAuthToken.mustache

@@ -1,6 +1,6 @@
 // <auto-generated>
 {{partial_header}}
-{{#nullableReferenceTypes}}#nullable enable{{/nullableReferenceTypes}}
+{{#nrt}}#nullable enable{{/nrt}}
 
 using System;
 using System.Linq;

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/README.mustache

@@ -62,7 +62,7 @@ namespace YourProject
         {
             var host = CreateHostBuilder(args).Build();{{#apiInfo}}{{#apis}}{{#-first}}
             var api = host.Services.GetRequiredService<{{interfacePrefix}}{{classname}}>();{{#operations}}{{#-first}}{{#operation}}{{#-first}}
-            ApiResponse<{{#returnType}}{{{.}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}> foo = await api.{{operationId}}WithHttpInfoAsync("todo");{{/-first}}{{/operation}}{{/-first}}{{/operations}}{{/-first}}{{/apis}}{{/apiInfo}}
+            ApiResponse<{{#returnType}}{{{.}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{nrt?}}> foo = await api.{{operationId}}WithHttpInfoAsync("todo");{{/-first}}{{/operation}}{{/-first}}{{/operations}}{{/-first}}{{/apis}}{{/apiInfo}}
         }
 
         public static IHostBuilder CreateHostBuilder(string[] args) => Host.CreateDefaultBuilder(args)

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/RateLimitProvider`1.mustache

@@ -1,6 +1,6 @@
 // <auto-generated>
 {{>partial_header}}
-{{#nullableReferenceTypes}}#nullable enable{{/nullableReferenceTypes}}
+{{#nrt}}#nullable enable{{/nrt}}
 
 using System;{{^netStandard}}
 using System.Threading.Channels;{{/netStandard}}{{#netStandard}}

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/TokenBase.mustache

@@ -1,6 +1,6 @@
 // <auto-generated>
 {{partial_header}}
-{{#nullableReferenceTypes}}#nullable enable{{/nullableReferenceTypes}}
+{{#nrt}}#nullable enable{{/nrt}}
 
 using System;
 
@@ -18,7 +18,7 @@ namespace {{packageName}}.Client
 
         internal TimeSpan? Timeout { get; set; }
         internal delegate void TokenBecameAvailableEventHandler(object sender);
-        internal event TokenBecameAvailableEventHandler{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} TokenBecameAvailable;
+        internal event TokenBecameAvailableEventHandler{{nrt?}} TokenBecameAvailable;
 
 
         /// <summary>

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/TokenContainer`1.mustache

@@ -1,6 +1,6 @@
 // <auto-generated>
 {{partial_header}}
-{{#nullableReferenceTypes}}#nullable enable{{/nullableReferenceTypes}}
+{{#nrt}}#nullable enable{{/nrt}}
 
 using System.Linq;
 using System.Collections.Generic;

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/TokenProvider`1.mustache

@@ -1,6 +1,6 @@
 // <auto-generated>
 {{>partial_header}}
-{{#nullableReferenceTypes}}#nullable enable{{/nullableReferenceTypes}}
+{{#nrt}}#nullable enable{{/nrt}}
 
 using System;
 using System.Linq;

modules/openapi-generator/src/main/resources/csharp-netcore/libraries/generichost/api.mustache

@@ -1,6 +1,6 @@
 // <auto-generated>
 {{>partial_header}}
-{{#nullableReferenceTypes}}#nullable enable{{/nullableReferenceTypes}}
+{{#nrt}}#nullable enable{{/nrt}}
 
 using System;
 using System.Collections.Generic;
@@ -34,8 +34,8 @@ namespace {{packageName}}.{{apiPackage}}
         /// <param name="{{paramName}}">{{description}}{{^required}} (optional{{#defaultValue}}, default to {{.}}{{/defaultValue}}){{/required}}</param>
         {{/allParams}}
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
-        /// <returns>Task&lt;ApiResponse&lt;{{#returnType}}{{returnType}}{{/returnType}}{{^returnType}}object{{/returnType}}{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}&gt;&gt;</returns>
+        /// <returns>Task&lt;ApiResponse&lt;{{#returnType}}{{returnType}}{{/returnType}}{{^returnType}}object{{/returnType}}{{nrt?}}&gt;&gt;</returns>
-        Task<ApiResponse<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}>> {{operationId}}WithHttpInfoAsync({{#allParams}}{{#required}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/required}}{{^required}}{{{dataType}}} {{paramName}} = null{{^-last}}, {{/-last}}{{/required}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}System.Threading.CancellationToken? cancellationToken = null);
+        Task<ApiResponse<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{nrt?}}>> {{operationId}}WithHttpInfoAsync({{#allParams}}{{#required}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/required}}{{^required}}{{{dataType}}} {{paramName}} = null{{^-last}}, {{/-last}}{{/required}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}System.Threading.CancellationToken? cancellationToken = null);
         
         /// <summary>
         /// {{summary}}
@@ -49,7 +49,7 @@ namespace {{packageName}}.{{apiPackage}}
         {{/allParams}}
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns>Task of ApiResponse&lt;{{#returnType}}{{returnType}}{{/returnType}}{{^returnType}}object{{/returnType}}&gt;</returns>
-        Task<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}> {{operationId}}Async({{#allParams}}{{#required}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/required}}{{^required}}{{{dataType}}} {{paramName}} = null{{^-last}}, {{/-last}}{{/required}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}System.Threading.CancellationToken? cancellationToken = null);{{#nullableReferenceTypes}}
+        Task<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{nrt?}}> {{operationId}}Async({{#allParams}}{{#required}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/required}}{{^required}}{{{dataType}}} {{paramName}} = null{{^-last}}, {{/-last}}{{/required}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}System.Threading.CancellationToken? cancellationToken = null);{{#nrt}}
         
         /// <summary>
         /// {{summary}}
@@ -62,7 +62,7 @@ namespace {{packageName}}.{{apiPackage}}
         {{/allParams}}
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns>Task of ApiResponse&lt;{{#returnType}}{{returnType}}{{/returnType}}{{^returnType}}object{{/returnType}}?&gt;</returns>
-        Task<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}> {{operationId}}OrDefaultAsync({{#allParams}}{{#required}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/required}}{{^required}}{{{dataType}}} {{paramName}} = null{{^-last}}, {{/-last}}{{/required}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}System.Threading.CancellationToken? cancellationToken = null);{{/nullableReferenceTypes}}{{^-last}}
+        Task<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{nrt?}}> {{operationId}}OrDefaultAsync({{#allParams}}{{#required}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/required}}{{^required}}{{{dataType}}} {{paramName}} = null{{^-last}}, {{/-last}}{{/required}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}System.Threading.CancellationToken? cancellationToken = null);{{/nrt}}{{^-last}}
 
         {{/-last}}{{/operation}}
     }
@@ -76,7 +76,7 @@ namespace {{packageName}}.{{apiPackage}}
         /// An event to track the health of the server. 
         /// If you store these event args, be sure to purge old event args to prevent a memory leak.
         /// </summary>
-        public event ClientUtils.EventHandler<ApiResponseEventArgs>{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} ApiResponded;
+        public event ClientUtils.EventHandler<ApiResponseEventArgs>{{nrt?}} ApiResponded;
 
         /// <summary>
         /// The logger
@@ -143,17 +143,17 @@ namespace {{packageName}}.{{apiPackage}}
         {{/allParams}}
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="{{#returnType}}{{.}}{{/returnType}}{{^returnType}}object{{/returnType}}"/>&gt;</returns>
-        public async Task<{{#returnType}}{{{.}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}> {{operationId}}Async({{#allParams}}{{#required}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/required}}{{^required}}{{{dataType}}} {{paramName}} = null{{^-last}}, {{/-last}}{{/required}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}System.Threading.CancellationToken? cancellationToken = null)
+        public async Task<{{#returnType}}{{{.}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{nrt?}}> {{operationId}}Async({{#allParams}}{{#required}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/required}}{{^required}}{{{dataType}}} {{paramName}} = null{{^-last}}, {{/-last}}{{/required}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}System.Threading.CancellationToken? cancellationToken = null)
         {
-            ApiResponse<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}> result = await {{operationId}}WithHttpInfoAsync({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}cancellationToken).ConfigureAwait(false);
+            ApiResponse<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{nrt?}}> result = await {{operationId}}WithHttpInfoAsync({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}cancellationToken).ConfigureAwait(false);
             
-            {{^nullableReferenceTypes}}{{#returnTypeIsPrimitive}}#pragma warning disable CS0472 // The result of the expression is always the same since a value of this type is never equal to 'null'
+            {{^nrt}}{{#returnTypeIsPrimitive}}#pragma warning disable CS0472 // The result of the expression is always the same since a value of this type is never equal to 'null'
-            {{/returnTypeIsPrimitive}}{{/nullableReferenceTypes}}if (result.Content == null){{^nullableReferenceTypes}}{{#returnTypeIsPrimitive}}
+            {{/returnTypeIsPrimitive}}{{/nrt}}if (result.Content == null){{^nrt}}{{#returnTypeIsPrimitive}}
-            #pragma warning disable CS0472 // The result of the expression is always the same since a value of this type is never equal to 'null'{{/returnTypeIsPrimitive}}{{/nullableReferenceTypes}}
+            #pragma warning disable CS0472 // The result of the expression is always the same since a value of this type is never equal to 'null'{{/returnTypeIsPrimitive}}{{/nrt}}
                 throw new ApiException(result.ReasonPhrase, result.StatusCode, result.RawContent);
 
             return result.Content;
-        }{{#nullableReferenceTypes}}
+        }{{#nrt}}
 
         /// <summary>
         /// {{summary}} {{notes}}
@@ -164,9 +164,9 @@ namespace {{packageName}}.{{apiPackage}}
         {{/allParams}}
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="{{#returnType}}{{returnType}}{{/returnType}}{{^returnType}}object{{/returnType}}"/>&gt;</returns>
-        public async Task<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}> {{operationId}}OrDefaultAsync({{#allParams}}{{#required}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/required}}{{^required}}{{{dataType}}} {{paramName}} = null{{^-last}}, {{/-last}}{{/required}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}System.Threading.CancellationToken? cancellationToken = null)
+        public async Task<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{nrt?}}> {{operationId}}OrDefaultAsync({{#allParams}}{{#required}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/required}}{{^required}}{{{dataType}}} {{paramName}} = null{{^-last}}, {{/-last}}{{/required}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}System.Threading.CancellationToken? cancellationToken = null)
         {
-            ApiResponse<{{#returnType}}{{{.}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}>{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} result = null;
+            ApiResponse<{{#returnType}}{{{.}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{nrt?}}>{{nrt?}} result = null;
             try 
             {
                 result = await {{operationId}}WithHttpInfoAsync({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}cancellationToken).ConfigureAwait(false);
@@ -178,7 +178,7 @@ namespace {{packageName}}.{{apiPackage}}
             return result != null && result.IsSuccessStatusCode
                 ? result.Content
                 : null;
-        }{{/nullableReferenceTypes}}{{^nullableReferenceTypes}}{{^returnTypeIsPrimitive}}
+        }{{/nrt}}{{^nrt}}{{^returnTypeIsPrimitive}}
 {{! Note that this method is a copy paste of above due to NRT complexities }}
         /// <summary>
         /// {{summary}} {{notes}}
@@ -189,9 +189,9 @@ namespace {{packageName}}.{{apiPackage}}
         {{/allParams}}
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="{{#returnType}}{{returnType}}{{/returnType}}{{^returnType}}object{{/returnType}}"/>&gt;</returns>
-        public async Task<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}> {{operationId}}OrDefaultAsync({{#allParams}}{{#required}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/required}}{{^required}}{{{dataType}}} {{paramName}} = null{{^-last}}, {{/-last}}{{/required}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}System.Threading.CancellationToken? cancellationToken = null)
+        public async Task<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{nrt?}}> {{operationId}}OrDefaultAsync({{#allParams}}{{#required}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/required}}{{^required}}{{{dataType}}} {{paramName}} = null{{^-last}}, {{/-last}}{{/required}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}System.Threading.CancellationToken? cancellationToken = null)
         {
-            ApiResponse<{{#returnType}}{{{.}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}>{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} result = null;
+            ApiResponse<{{#returnType}}{{{.}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{nrt?}}>{{nrt?}} result = null;
             try 
             {
                 result = await {{operationId}}WithHttpInfoAsync({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}cancellationToken).ConfigureAwait(false);
@@ -204,7 +204,7 @@ namespace {{packageName}}.{{apiPackage}}
                 ? result.Content
                 : null;
         }
-        {{/returnTypeIsPrimitive}}{{/nullableReferenceTypes}}
+        {{/returnTypeIsPrimitive}}{{/nrt}}
 
         /// <summary>
         /// {{summary}} {{notes}}
@@ -215,24 +215,24 @@ namespace {{packageName}}.{{apiPackage}}
         {{/allParams}}
         /// <param name="cancellationToken">Cancellation Token to cancel the request.</param>
         /// <returns><see cref="Task"/>&lt;<see cref="ApiResponse{T}"/>&gt; where T : <see cref="{{#returnType}}{{returnType}}{{/returnType}}{{^returnType}}object{{/returnType}}"/></returns>
-        public async Task<ApiResponse<{{#returnType}}{{{.}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}>> {{operationId}}WithHttpInfoAsync({{#allParams}}{{#required}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/required}}{{^required}}{{{dataType}}} {{paramName}} = null{{^-last}}, {{/-last}}{{/required}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}System.Threading.CancellationToken? cancellationToken = null)
+        public async Task<ApiResponse<{{#returnType}}{{{.}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{nrt?}}>> {{operationId}}WithHttpInfoAsync({{#allParams}}{{#required}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/required}}{{^required}}{{{dataType}}} {{paramName}} = null{{^-last}}, {{/-last}}{{/required}}{{/allParams}}{{#allParams.0}}, {{/allParams.0}}System.Threading.CancellationToken? cancellationToken = null)
         {
             try
             {
-                {{#hasRequiredParams}}#pragma warning disable CS0472 // The result of the expression is always the same since a value of this type is never equal to 'null'{{/hasRequiredParams}}{{#allParams}}{{#required}}{{#nullableReferenceTypes}}
+                {{#hasRequiredParams}}#pragma warning disable CS0472 // The result of the expression is always the same since a value of this type is never equal to 'null'{{/hasRequiredParams}}{{#allParams}}{{#required}}{{#nrt}}
 
                 if ({{paramName}} == null)
-                    throw new ArgumentNullException(nameof({{paramName}}));{{/nullableReferenceTypes}}{{^nullableReferenceTypes}}{{^vendorExtensions.x-csharp-value-type}}
+                    throw new ArgumentNullException(nameof({{paramName}}));{{/nrt}}{{^nrt}}{{^vendorExtensions.x-csharp-value-type}}
                     
                 if ({{paramName}} == null)
-                    throw new ArgumentNullException(nameof({{paramName}}));{{/vendorExtensions.x-csharp-value-type}}{{/nullableReferenceTypes}}{{/required}}{{/allParams}}{{#hasRequiredParams}}
+                    throw new ArgumentNullException(nameof({{paramName}}));{{/vendorExtensions.x-csharp-value-type}}{{/nrt}}{{/required}}{{/allParams}}{{#hasRequiredParams}}
                     
                 #pragma warning disable CS0472 // The result of the expression is always the same since a value of this type is never equal to 'null'
                 
                 {{/hasRequiredParams}}using (HttpRequestMessage request = new HttpRequestMessage())
                 {
                     UriBuilder uriBuilder = new UriBuilder();
-                    uriBuilder.Host = HttpClient.BaseAddress{{#nullableReferenceTypes}}!{{/nullableReferenceTypes}}.Host;
+                    uriBuilder.Host = HttpClient.BaseAddress{{nrt!}}.Host;
                     uriBuilder.Scheme = ClientUtils.SCHEME;
                     uriBuilder.Path = ClientUtils.CONTEXT_PATH + "{{path}}";{{#pathParams}}{{#required}}
                     uriBuilder.Path = uriBuilder.Path.Replace("%7B{{baseName}}%7D", Uri.EscapeDataString({{paramName}}.ToString()));{{/required}}{{^required}}
@@ -246,10 +246,10 @@ namespace {{packageName}}.{{apiPackage}}
                     System.Collections.Specialized.NameValueCollection parseQueryString = System.Web.HttpUtility.ParseQueryString(string.Empty);{{/isKeyInQuery}}{{/isApiKey}}{{/authMethods}}{{/queryParams}}{{#queryParams}}{{#required}}{{#-first}}
 
     {{! all the redundant tags here are to get the spacing just right }}
-                    {{/-first}}{{/required}}{{/queryParams}}{{#queryParams}}{{#required}}parseQueryString["{{baseName}}"] = Uri.EscapeDataString({{paramName}}.ToString(){{#nullableReferenceTypes}}!{{/nullableReferenceTypes}});
+                    {{/-first}}{{/required}}{{/queryParams}}{{#queryParams}}{{#required}}parseQueryString["{{baseName}}"] = Uri.EscapeDataString({{paramName}}.ToString(){{nrt!}});
                     {{/required}}{{/queryParams}}{{#queryParams}}{{#-first}}
                     {{/-first}}{{/queryParams}}{{#queryParams}}{{^required}}if ({{paramName}} != null)
-                        parseQueryString["{{baseName}}"] = Uri.EscapeDataString({{paramName}}.ToString(){{#nullableReferenceTypes}}!{{/nullableReferenceTypes}});
+                        parseQueryString["{{baseName}}"] = Uri.EscapeDataString({{paramName}}.ToString(){{nrt!}});
 
                     {{/required}}{{#-last}}uriBuilder.Query = parseQueryString.ToString();{{/-last}}{{/queryParams}}{{#headerParams}}{{#required}}
                     
@@ -262,14 +262,14 @@ namespace {{packageName}}.{{apiPackage}}
 
                     request.Content = multipartContent;
                     
-                    List<KeyValuePair<string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}, string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}>> formParams = new List<KeyValuePair<string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}, string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}>>();
+                    List<KeyValuePair<string{{nrt?}}, string{{nrt?}}>> formParams = new List<KeyValuePair<string{{nrt?}}, string{{nrt?}}>>();
 
                     multipartContent.Add(new FormUrlEncodedContent(formParams));{{/-first}}{{^isFile}}{{#required}}
                     
-                    formParams.Add(new KeyValuePair<string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}, string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}>("{{baseName}}", ClientUtils.ParameterToString({{paramName}})));{{/required}}{{^required}}
+                    formParams.Add(new KeyValuePair<string{{nrt?}}, string{{nrt?}}>("{{baseName}}", ClientUtils.ParameterToString({{paramName}})));{{/required}}{{^required}}
 
                     if ({{paramName}} != null)
-                        formParams.Add(new KeyValuePair<string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}, string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}>("{{baseName}}", ClientUtils.ParameterToString({{paramName}})));{{/required}}{{/isFile}}{{#isFile}}{{#required}}
+                        formParams.Add(new KeyValuePair<string{{nrt?}}, string{{nrt?}}>("{{baseName}}", ClientUtils.ParameterToString({{paramName}})));{{/required}}{{/isFile}}{{#isFile}}{{#required}}
                     
                     multipartContent.Add(new StreamContent({{paramName}}));{{/required}}{{^required}}
                     
@@ -322,7 +322,7 @@ namespace {{packageName}}.{{apiPackage}}
 
                     tokens.Add(signatureToken);
 
-                    string requestBody = await request.Content{{#nullableReferenceTypes}}!{{/nullableReferenceTypes}}.ReadAsStringAsync({{^netStandard}}{{^netcoreapp3.1}}cancellationToken.GetValueOrDefault(){{/netcoreapp3.1}}{{/netStandard}}).ConfigureAwait(false);
+                    string requestBody = await request.Content{{nrt!}}.ReadAsStringAsync({{^netStandard}}{{^netcoreapp3.1}}cancellationToken.GetValueOrDefault(){{/netcoreapp3.1}}{{/netStandard}}).ConfigureAwait(false);
 
                     signatureToken.UseInHeader(request, requestBody, cancellationToken);{{/isHttpSignature}}{{/authMethods}}{{#consumes}}{{#-first}}
                     
@@ -331,7 +331,7 @@ namespace {{packageName}}.{{apiPackage}}
                         {{/-last}}{{#-last}} 
                     };{{/-last}}{{/consumes}}{{#consumes}}{{#-first}}
                     
-                    string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} contentType = ClientUtils.SelectHeaderContentType(contentTypes);
+                    string{{nrt?}} contentType = ClientUtils.SelectHeaderContentType(contentTypes);
 
                     if (contentType != null)
                         request.Content.Headers.Add("ContentType", contentType);{{/-first}}{{/consumes}}{{#produces}}{{#-first}}
@@ -341,7 +341,7 @@ namespace {{packageName}}.{{apiPackage}}
                         {{/-last}}{{/produces}}{{#produces}}{{#-last}} 
                     };{{/-last}}{{/produces}}{{#produces}}{{#-first}}
                     
-                    string{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}} accept = ClientUtils.SelectHeaderAccept(accepts);
+                    string{{nrt?}} accept = ClientUtils.SelectHeaderAccept(accepts);
 
                     if (accept != null)
                         request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue(accept));
@@ -367,7 +367,7 @@ namespace {{packageName}}.{{apiPackage}}
                             }
                         }
 
-                        ApiResponse<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}> apiResponse = new ApiResponse<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{#nullableReferenceTypes}}?{{/nullableReferenceTypes}}>(responseMessage, responseContent);
+                        ApiResponse<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{nrt?}}> apiResponse = new ApiResponse<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}{{nrt?}}>(responseMessage, responseContent);
 
                         if (apiResponse.IsSuccessStatusCode)
                             apiResponse.Content = Newtonsoft.Json.JsonConvert.DeserializeObject<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}object{{/returnType}}>(apiResponse.RawContent, ClientUtils.JsonSerializerSettings);{{#authMethods}}

modules/openapi-generator/src/main/resources/csharp-netcore/netcore_project.mustache

@@ -19,10 +19,8 @@
     <RepositoryUrl>https://{{{gitHost}}}/{{{gitUserId}}}/{{{gitRepoId}}}.git</RepositoryUrl>
     <RepositoryType>git</RepositoryType>{{#releaseNote}}
     <PackageReleaseNotes>{{.}}</PackageReleaseNotes>{{/releaseNote}}{{#packageTags}}
-    <PackageTags>{{{.}}}</PackageTags>{{/packageTags}}
+    <PackageTags>{{{.}}}</PackageTags>{{/packageTags}}{{#nrt}}
-    {{#nullableReferenceTypes}}
+    <Nullable>annotations</Nullable>{{/nrt}}
-    <Nullable>annotations</Nullable>
-    {{/nullableReferenceTypes}}
   </PropertyGroup>
 
   <ItemGroup>

modules/openapi-generator/src/main/resources/csharp-netcore/netcore_testproject.mustache

@@ -4,8 +4,8 @@
     <AssemblyName>{{testPackageName}}</AssemblyName>
     <RootNamespace>{{testPackageName}}</RootNamespace>
     <TargetFramework{{#multiTarget}}s{{/multiTarget}}>{{testTargetFramework}}</TargetFramework{{#multiTarget}}s{{/multiTarget}}>
-    <IsPackable>false</IsPackable>{{#nullableReferenceTypes}}
+    <IsPackable>false</IsPackable>{{#nrt}}
-    <Nullable>annotations</Nullable>{{/nullableReferenceTypes}}
+    <Nullable>annotations</Nullable>{{/nrt}}
   </PropertyGroup>
 
   <ItemGroup>