diff --git a/modules/openapi-generator/src/main/resources/csharp/auth/OAuthAuthenticator.mustache b/modules/openapi-generator/src/main/resources/csharp/auth/OAuthAuthenticator.mustache
index d71f262a810f..c336c8ad5ccf 100644
--- a/modules/openapi-generator/src/main/resources/csharp/auth/OAuthAuthenticator.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp/auth/OAuthAuthenticator.mustache
@@ -11,8 +11,25 @@ namespace {{packageName}}.Client.Auth
     /// <summary>
     /// An authenticator for OAuth2 authentication flows
     /// </summary>
-    public class OAuthAuthenticator : AuthenticatorBase
+    public class OAuthAuthenticator : IAuthenticator
     {
+        private TokenResponse{{nrt?}} _token;
+
+        /// <summary>
+        /// Returns the current authentication token. Can return null if there is no authentication token, or it has expired.
+        /// </summary>
+        public string{{nrt?}} Token
+        {
+            get
+            {
+                if (_token == null) return null;
+                if (_token.ExpiresIn == null) return _token.AccessToken;
+                if (_token.ExpiresAt < DateTime.Now) return null;
+
+                return _token.AccessToken;
+            }
+        }
+
         readonly string _tokenUrl;
         readonly string _clientId;
         readonly string _clientSecret;
@@ -31,7 +48,7 @@ namespace {{packageName}}.Client.Auth
             string{{nrt?}} scope,
             OAuthFlow? flow,
             JsonSerializerSettings serializerSettings,
-            IReadableConfiguration configuration) : base("")
+            IReadableConfiguration configuration)
         {
             _tokenUrl = tokenUrl;
             _clientId = clientId;
@@ -62,9 +79,8 @@ namespace {{packageName}}.Client.Auth
         /// <summary>
         /// Creates an authentication parameter from an access token.
         /// </summary>
-        /// <param name="accessToken">Access token to create a parameter from.</param>
         /// <returns>An authentication parameter.</returns>
-        protected override async ValueTask<Parameter> GetAuthenticationParameter(string accessToken)
+        protected async ValueTask<Parameter> GetAuthenticationParameter()
         {
             var token = string.IsNullOrEmpty(Token) ? await GetToken().ConfigureAwait(false) : Token;
             return new HeaderParameter(KnownHeaders.Authorization, token);
@@ -76,31 +92,45 @@ namespace {{packageName}}.Client.Auth
         /// <returns>An authentication token.</returns>
         async Task<string> GetToken()
         {
-            var client = new RestClient(_tokenUrl,
-                configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
-
-            var request = new RestRequest()
-                .AddParameter("grant_type", _grantType)
-                .AddParameter("client_id", _clientId)
-                .AddParameter("client_secret", _clientSecret);
+            var client = new RestClient(_tokenUrl, configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
 
+            var request = new RestRequest();
+            if (!string.IsNullOrWhiteSpace(_token?.RefreshToken))
+            {
+                request.AddParameter("grant_type", "refresh_token")
+                    .AddParameter("refresh_token", _token.RefreshToken);
+            }
+            else
+            {
+                request
+                    .AddParameter("grant_type", _grantType)
+                    .AddParameter("client_id", _clientId)
+                    .AddParameter("client_secret", _clientSecret);
+            }
             if (!string.IsNullOrEmpty(_scope))
             {
                 request.AddParameter("scope", _scope);
             }
-
-            var response = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
-            
+            _token = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
             // RFC6749 - token_type is case insensitive.
             // RFC6750 - In Authorization header Bearer should be capitalized.
             // Fix the capitalization irrespective of token_type casing.
-            switch (response.TokenType?.ToLower())
+            switch (_token?.TokenType?.ToLower())
             {
                 case "bearer":
-                    return $"Bearer {response.AccessToken}";
+                    return $"Bearer {_token.AccessToken}";
                 default:
-                    return $"{response.TokenType} {response.AccessToken}";
+                    return $"{_token?.TokenType} {_token?.AccessToken}";
             }
         }
+
+        /// <summary>
+        /// Retrieves the authentication token (creating a new one if necessary) and adds it to the current request
+        /// </summary>
+        /// <param name="client"></param>
+        /// <param name="request"></param>
+        /// <returns></returns>
+        public async ValueTask Authenticate(IRestClient client, RestRequest request)
+            => request.AddOrUpdateParameter(await GetAuthenticationParameter().ConfigureAwait(false));
     }
 }
diff --git a/modules/openapi-generator/src/main/resources/csharp/auth/TokenResponse.mustache b/modules/openapi-generator/src/main/resources/csharp/auth/TokenResponse.mustache
index f118b97a9dd5..7a72e04c12c2 100644
--- a/modules/openapi-generator/src/main/resources/csharp/auth/TokenResponse.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp/auth/TokenResponse.mustache
@@ -1,5 +1,6 @@
 {{>partial_header}}
 
+using System;
 using Newtonsoft.Json;
 
 namespace {{packageName}}.Client.Auth
@@ -10,5 +11,14 @@ namespace {{packageName}}.Client.Auth
         public string TokenType { get; set; }
         [JsonProperty("access_token")]
         public string AccessToken { get; set; }
+        [JsonProperty("expires_in")]
+        public int? ExpiresIn { get; set; }
+        [JsonProperty("created")]
+        public DateTime? Created { get; set; }
+
+        [JsonProperty("refresh_token")]
+        public string{{nrt?}} RefreshToken { get; set; }
+
+        public DateTime? ExpiresAt => ExpiresIn == null ? null : Created?.AddSeconds(ExpiresIn.Value);
     }
 }
\ No newline at end of file
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
index 516b93d2f6aa..e731f1c71bea 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
@@ -19,8 +19,25 @@ namespace Org.OpenAPITools.Client.Auth
     /// <summary>
     /// An authenticator for OAuth2 authentication flows
     /// </summary>
-    public class OAuthAuthenticator : AuthenticatorBase
+    public class OAuthAuthenticator : IAuthenticator
     {
+        private TokenResponse _token;
+
+        /// <summary>
+        /// Returns the current authentication token. Can return null if there is no authentication token, or it has expired.
+        /// </summary>
+        public string Token
+        {
+            get
+            {
+                if (_token == null) return null;
+                if (_token.ExpiresIn == null) return _token.AccessToken;
+                if (_token.ExpiresAt < DateTime.Now) return null;
+
+                return _token.AccessToken;
+            }
+        }
+
         readonly string _tokenUrl;
         readonly string _clientId;
         readonly string _clientSecret;
@@ -39,7 +56,7 @@ public OAuthAuthenticator(
             string scope,
             OAuthFlow? flow,
             JsonSerializerSettings serializerSettings,
-            IReadableConfiguration configuration) : base("")
+            IReadableConfiguration configuration)
         {
             _tokenUrl = tokenUrl;
             _clientId = clientId;
@@ -70,9 +87,8 @@ public OAuthAuthenticator(
         /// <summary>
         /// Creates an authentication parameter from an access token.
         /// </summary>
-        /// <param name="accessToken">Access token to create a parameter from.</param>
         /// <returns>An authentication parameter.</returns>
-        protected override async ValueTask<Parameter> GetAuthenticationParameter(string accessToken)
+        protected async ValueTask<Parameter> GetAuthenticationParameter()
         {
             var token = string.IsNullOrEmpty(Token) ? await GetToken().ConfigureAwait(false) : Token;
             return new HeaderParameter(KnownHeaders.Authorization, token);
@@ -84,31 +100,45 @@ protected override async ValueTask<Parameter> GetAuthenticationParameter(string
         /// <returns>An authentication token.</returns>
         async Task<string> GetToken()
         {
-            var client = new RestClient(_tokenUrl,
-                configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
-
-            var request = new RestRequest()
-                .AddParameter("grant_type", _grantType)
-                .AddParameter("client_id", _clientId)
-                .AddParameter("client_secret", _clientSecret);
+            var client = new RestClient(_tokenUrl, configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
 
+            var request = new RestRequest();
+            if (!string.IsNullOrWhiteSpace(_token?.RefreshToken))
+            {
+                request.AddParameter("grant_type", "refresh_token")
+                    .AddParameter("refresh_token", _token.RefreshToken);
+            }
+            else
+            {
+                request
+                    .AddParameter("grant_type", _grantType)
+                    .AddParameter("client_id", _clientId)
+                    .AddParameter("client_secret", _clientSecret);
+            }
             if (!string.IsNullOrEmpty(_scope))
             {
                 request.AddParameter("scope", _scope);
             }
-
-            var response = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
-            
+            _token = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
             // RFC6749 - token_type is case insensitive.
             // RFC6750 - In Authorization header Bearer should be capitalized.
             // Fix the capitalization irrespective of token_type casing.
-            switch (response.TokenType?.ToLower())
+            switch (_token?.TokenType?.ToLower())
             {
                 case "bearer":
-                    return $"Bearer {response.AccessToken}";
+                    return $"Bearer {_token.AccessToken}";
                 default:
-                    return $"{response.TokenType} {response.AccessToken}";
+                    return $"{_token?.TokenType} {_token?.AccessToken}";
             }
         }
+
+        /// <summary>
+        /// Retrieves the authentication token (creating a new one if necessary) and adds it to the current request
+        /// </summary>
+        /// <param name="client"></param>
+        /// <param name="request"></param>
+        /// <returns></returns>
+        public async ValueTask Authenticate(IRestClient client, RestRequest request)
+            => request.AddOrUpdateParameter(await GetAuthenticationParameter().ConfigureAwait(false));
     }
 }
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
index 21fd27c376fa..5ff4349979fd 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
@@ -8,6 +8,7 @@
  */
 
 
+using System;
 using Newtonsoft.Json;
 
 namespace Org.OpenAPITools.Client.Auth
@@ -18,5 +19,14 @@ class TokenResponse
         public string TokenType { get; set; }
         [JsonProperty("access_token")]
         public string AccessToken { get; set; }
+        [JsonProperty("expires_in")]
+        public int? ExpiresIn { get; set; }
+        [JsonProperty("created")]
+        public DateTime? Created { get; set; }
+
+        [JsonProperty("refresh_token")]
+        public string RefreshToken { get; set; }
+
+        public DateTime? ExpiresAt => ExpiresIn == null ? null : Created?.AddSeconds(ExpiresIn.Value);
     }
 }
\ No newline at end of file
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
index d7fb1293b34b..6c6817ef501a 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
@@ -19,8 +19,25 @@ namespace Org.OpenAPITools.Client.Auth
     /// <summary>
     /// An authenticator for OAuth2 authentication flows
     /// </summary>
-    public class OAuthAuthenticator : AuthenticatorBase
+    public class OAuthAuthenticator : IAuthenticator
     {
+        private TokenResponse _token;
+
+        /// <summary>
+        /// Returns the current authentication token. Can return null if there is no authentication token, or it has expired.
+        /// </summary>
+        public string Token
+        {
+            get
+            {
+                if (_token == null) return null;
+                if (_token.ExpiresIn == null) return _token.AccessToken;
+                if (_token.ExpiresAt < DateTime.Now) return null;
+
+                return _token.AccessToken;
+            }
+        }
+
         readonly string _tokenUrl;
         readonly string _clientId;
         readonly string _clientSecret;
@@ -39,7 +56,7 @@ public OAuthAuthenticator(
             string scope,
             OAuthFlow? flow,
             JsonSerializerSettings serializerSettings,
-            IReadableConfiguration configuration) : base("")
+            IReadableConfiguration configuration)
         {
             _tokenUrl = tokenUrl;
             _clientId = clientId;
@@ -70,9 +87,8 @@ public OAuthAuthenticator(
         /// <summary>
         /// Creates an authentication parameter from an access token.
         /// </summary>
-        /// <param name="accessToken">Access token to create a parameter from.</param>
         /// <returns>An authentication parameter.</returns>
-        protected override async ValueTask<Parameter> GetAuthenticationParameter(string accessToken)
+        protected async ValueTask<Parameter> GetAuthenticationParameter()
         {
             var token = string.IsNullOrEmpty(Token) ? await GetToken().ConfigureAwait(false) : Token;
             return new HeaderParameter(KnownHeaders.Authorization, token);
@@ -84,31 +100,45 @@ protected override async ValueTask<Parameter> GetAuthenticationParameter(string
         /// <returns>An authentication token.</returns>
         async Task<string> GetToken()
         {
-            var client = new RestClient(_tokenUrl,
-                configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
-
-            var request = new RestRequest()
-                .AddParameter("grant_type", _grantType)
-                .AddParameter("client_id", _clientId)
-                .AddParameter("client_secret", _clientSecret);
+            var client = new RestClient(_tokenUrl, configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
 
+            var request = new RestRequest();
+            if (!string.IsNullOrWhiteSpace(_token?.RefreshToken))
+            {
+                request.AddParameter("grant_type", "refresh_token")
+                    .AddParameter("refresh_token", _token.RefreshToken);
+            }
+            else
+            {
+                request
+                    .AddParameter("grant_type", _grantType)
+                    .AddParameter("client_id", _clientId)
+                    .AddParameter("client_secret", _clientSecret);
+            }
             if (!string.IsNullOrEmpty(_scope))
             {
                 request.AddParameter("scope", _scope);
             }
-
-            var response = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
-            
+            _token = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
             // RFC6749 - token_type is case insensitive.
             // RFC6750 - In Authorization header Bearer should be capitalized.
             // Fix the capitalization irrespective of token_type casing.
-            switch (response.TokenType?.ToLower())
+            switch (_token?.TokenType?.ToLower())
             {
                 case "bearer":
-                    return $"Bearer {response.AccessToken}";
+                    return $"Bearer {_token.AccessToken}";
                 default:
-                    return $"{response.TokenType} {response.AccessToken}";
+                    return $"{_token?.TokenType} {_token?.AccessToken}";
             }
         }
+
+        /// <summary>
+        /// Retrieves the authentication token (creating a new one if necessary) and adds it to the current request
+        /// </summary>
+        /// <param name="client"></param>
+        /// <param name="request"></param>
+        /// <returns></returns>
+        public async ValueTask Authenticate(IRestClient client, RestRequest request)
+            => request.AddOrUpdateParameter(await GetAuthenticationParameter().ConfigureAwait(false));
     }
 }
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
index 0a94e17e1228..95e03c36e105 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
@@ -8,6 +8,7 @@
  */
 
 
+using System;
 using Newtonsoft.Json;
 
 namespace Org.OpenAPITools.Client.Auth
@@ -18,5 +19,14 @@ class TokenResponse
         public string TokenType { get; set; }
         [JsonProperty("access_token")]
         public string AccessToken { get; set; }
+        [JsonProperty("expires_in")]
+        public int? ExpiresIn { get; set; }
+        [JsonProperty("created")]
+        public DateTime? Created { get; set; }
+
+        [JsonProperty("refresh_token")]
+        public string RefreshToken { get; set; }
+
+        public DateTime? ExpiresAt => ExpiresIn == null ? null : Created?.AddSeconds(ExpiresIn.Value);
     }
 }
\ No newline at end of file
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
index d7fb1293b34b..6c6817ef501a 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
@@ -19,8 +19,25 @@ namespace Org.OpenAPITools.Client.Auth
     /// <summary>
     /// An authenticator for OAuth2 authentication flows
     /// </summary>
-    public class OAuthAuthenticator : AuthenticatorBase
+    public class OAuthAuthenticator : IAuthenticator
     {
+        private TokenResponse _token;
+
+        /// <summary>
+        /// Returns the current authentication token. Can return null if there is no authentication token, or it has expired.
+        /// </summary>
+        public string Token
+        {
+            get
+            {
+                if (_token == null) return null;
+                if (_token.ExpiresIn == null) return _token.AccessToken;
+                if (_token.ExpiresAt < DateTime.Now) return null;
+
+                return _token.AccessToken;
+            }
+        }
+
         readonly string _tokenUrl;
         readonly string _clientId;
         readonly string _clientSecret;
@@ -39,7 +56,7 @@ public OAuthAuthenticator(
             string scope,
             OAuthFlow? flow,
             JsonSerializerSettings serializerSettings,
-            IReadableConfiguration configuration) : base("")
+            IReadableConfiguration configuration)
         {
             _tokenUrl = tokenUrl;
             _clientId = clientId;
@@ -70,9 +87,8 @@ public OAuthAuthenticator(
         /// <summary>
         /// Creates an authentication parameter from an access token.
         /// </summary>
-        /// <param name="accessToken">Access token to create a parameter from.</param>
         /// <returns>An authentication parameter.</returns>
-        protected override async ValueTask<Parameter> GetAuthenticationParameter(string accessToken)
+        protected async ValueTask<Parameter> GetAuthenticationParameter()
         {
             var token = string.IsNullOrEmpty(Token) ? await GetToken().ConfigureAwait(false) : Token;
             return new HeaderParameter(KnownHeaders.Authorization, token);
@@ -84,31 +100,45 @@ protected override async ValueTask<Parameter> GetAuthenticationParameter(string
         /// <returns>An authentication token.</returns>
         async Task<string> GetToken()
         {
-            var client = new RestClient(_tokenUrl,
-                configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
-
-            var request = new RestRequest()
-                .AddParameter("grant_type", _grantType)
-                .AddParameter("client_id", _clientId)
-                .AddParameter("client_secret", _clientSecret);
+            var client = new RestClient(_tokenUrl, configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
 
+            var request = new RestRequest();
+            if (!string.IsNullOrWhiteSpace(_token?.RefreshToken))
+            {
+                request.AddParameter("grant_type", "refresh_token")
+                    .AddParameter("refresh_token", _token.RefreshToken);
+            }
+            else
+            {
+                request
+                    .AddParameter("grant_type", _grantType)
+                    .AddParameter("client_id", _clientId)
+                    .AddParameter("client_secret", _clientSecret);
+            }
             if (!string.IsNullOrEmpty(_scope))
             {
                 request.AddParameter("scope", _scope);
             }
-
-            var response = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
-            
+            _token = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
             // RFC6749 - token_type is case insensitive.
             // RFC6750 - In Authorization header Bearer should be capitalized.
             // Fix the capitalization irrespective of token_type casing.
-            switch (response.TokenType?.ToLower())
+            switch (_token?.TokenType?.ToLower())
             {
                 case "bearer":
-                    return $"Bearer {response.AccessToken}";
+                    return $"Bearer {_token.AccessToken}";
                 default:
-                    return $"{response.TokenType} {response.AccessToken}";
+                    return $"{_token?.TokenType} {_token?.AccessToken}";
             }
         }
+
+        /// <summary>
+        /// Retrieves the authentication token (creating a new one if necessary) and adds it to the current request
+        /// </summary>
+        /// <param name="client"></param>
+        /// <param name="request"></param>
+        /// <returns></returns>
+        public async ValueTask Authenticate(IRestClient client, RestRequest request)
+            => request.AddOrUpdateParameter(await GetAuthenticationParameter().ConfigureAwait(false));
     }
 }
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
index 0a94e17e1228..95e03c36e105 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
@@ -8,6 +8,7 @@
  */
 
 
+using System;
 using Newtonsoft.Json;
 
 namespace Org.OpenAPITools.Client.Auth
@@ -18,5 +19,14 @@ class TokenResponse
         public string TokenType { get; set; }
         [JsonProperty("access_token")]
         public string AccessToken { get; set; }
+        [JsonProperty("expires_in")]
+        public int? ExpiresIn { get; set; }
+        [JsonProperty("created")]
+        public DateTime? Created { get; set; }
+
+        [JsonProperty("refresh_token")]
+        public string RefreshToken { get; set; }
+
+        public DateTime? ExpiresAt => ExpiresIn == null ? null : Created?.AddSeconds(ExpiresIn.Value);
     }
 }
\ No newline at end of file
diff --git a/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs b/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
index ce6261390c32..bcccf1e83f6f 100644
--- a/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
+++ b/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
@@ -19,8 +19,25 @@ namespace Org.OpenAPITools.Client.Auth
     /// <summary>
     /// An authenticator for OAuth2 authentication flows
     /// </summary>
-    public class OAuthAuthenticator : AuthenticatorBase
+    public class OAuthAuthenticator : IAuthenticator
     {
+        private TokenResponse? _token;
+
+        /// <summary>
+        /// Returns the current authentication token. Can return null if there is no authentication token, or it has expired.
+        /// </summary>
+        public string? Token
+        {
+            get
+            {
+                if (_token == null) return null;
+                if (_token.ExpiresIn == null) return _token.AccessToken;
+                if (_token.ExpiresAt < DateTime.Now) return null;
+
+                return _token.AccessToken;
+            }
+        }
+
         readonly string _tokenUrl;
         readonly string _clientId;
         readonly string _clientSecret;
@@ -39,7 +56,7 @@ public OAuthAuthenticator(
             string? scope,
             OAuthFlow? flow,
             JsonSerializerSettings serializerSettings,
-            IReadableConfiguration configuration) : base("")
+            IReadableConfiguration configuration)
         {
             _tokenUrl = tokenUrl;
             _clientId = clientId;
@@ -70,9 +87,8 @@ public OAuthAuthenticator(
         /// <summary>
         /// Creates an authentication parameter from an access token.
         /// </summary>
-        /// <param name="accessToken">Access token to create a parameter from.</param>
         /// <returns>An authentication parameter.</returns>
-        protected override async ValueTask<Parameter> GetAuthenticationParameter(string accessToken)
+        protected async ValueTask<Parameter> GetAuthenticationParameter()
         {
             var token = string.IsNullOrEmpty(Token) ? await GetToken().ConfigureAwait(false) : Token;
             return new HeaderParameter(KnownHeaders.Authorization, token);
@@ -84,31 +100,45 @@ protected override async ValueTask<Parameter> GetAuthenticationParameter(string
         /// <returns>An authentication token.</returns>
         async Task<string> GetToken()
         {
-            var client = new RestClient(_tokenUrl,
-                configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
-
-            var request = new RestRequest()
-                .AddParameter("grant_type", _grantType)
-                .AddParameter("client_id", _clientId)
-                .AddParameter("client_secret", _clientSecret);
+            var client = new RestClient(_tokenUrl, configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
 
+            var request = new RestRequest();
+            if (!string.IsNullOrWhiteSpace(_token?.RefreshToken))
+            {
+                request.AddParameter("grant_type", "refresh_token")
+                    .AddParameter("refresh_token", _token.RefreshToken);
+            }
+            else
+            {
+                request
+                    .AddParameter("grant_type", _grantType)
+                    .AddParameter("client_id", _clientId)
+                    .AddParameter("client_secret", _clientSecret);
+            }
             if (!string.IsNullOrEmpty(_scope))
             {
                 request.AddParameter("scope", _scope);
             }
-
-            var response = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
-            
+            _token = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
             // RFC6749 - token_type is case insensitive.
             // RFC6750 - In Authorization header Bearer should be capitalized.
             // Fix the capitalization irrespective of token_type casing.
-            switch (response.TokenType?.ToLower())
+            switch (_token?.TokenType?.ToLower())
             {
                 case "bearer":
-                    return $"Bearer {response.AccessToken}";
+                    return $"Bearer {_token.AccessToken}";
                 default:
-                    return $"{response.TokenType} {response.AccessToken}";
+                    return $"{_token?.TokenType} {_token?.AccessToken}";
             }
         }
+
+        /// <summary>
+        /// Retrieves the authentication token (creating a new one if necessary) and adds it to the current request
+        /// </summary>
+        /// <param name="client"></param>
+        /// <param name="request"></param>
+        /// <returns></returns>
+        public async ValueTask Authenticate(IRestClient client, RestRequest request)
+            => request.AddOrUpdateParameter(await GetAuthenticationParameter().ConfigureAwait(false));
     }
 }
diff --git a/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs b/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
index 0a94e17e1228..da4f4499b1cc 100644
--- a/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
+++ b/samples/client/petstore/csharp/restsharp/net7/EnumMappings/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
@@ -8,6 +8,7 @@
  */
 
 
+using System;
 using Newtonsoft.Json;
 
 namespace Org.OpenAPITools.Client.Auth
@@ -18,5 +19,14 @@ class TokenResponse
         public string TokenType { get; set; }
         [JsonProperty("access_token")]
         public string AccessToken { get; set; }
+        [JsonProperty("expires_in")]
+        public int? ExpiresIn { get; set; }
+        [JsonProperty("created")]
+        public DateTime? Created { get; set; }
+
+        [JsonProperty("refresh_token")]
+        public string? RefreshToken { get; set; }
+
+        public DateTime? ExpiresAt => ExpiresIn == null ? null : Created?.AddSeconds(ExpiresIn.Value);
     }
 }
\ No newline at end of file
diff --git a/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs b/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
index ce6261390c32..bcccf1e83f6f 100644
--- a/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
+++ b/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
@@ -19,8 +19,25 @@ namespace Org.OpenAPITools.Client.Auth
     /// <summary>
     /// An authenticator for OAuth2 authentication flows
     /// </summary>
-    public class OAuthAuthenticator : AuthenticatorBase
+    public class OAuthAuthenticator : IAuthenticator
     {
+        private TokenResponse? _token;
+
+        /// <summary>
+        /// Returns the current authentication token. Can return null if there is no authentication token, or it has expired.
+        /// </summary>
+        public string? Token
+        {
+            get
+            {
+                if (_token == null) return null;
+                if (_token.ExpiresIn == null) return _token.AccessToken;
+                if (_token.ExpiresAt < DateTime.Now) return null;
+
+                return _token.AccessToken;
+            }
+        }
+
         readonly string _tokenUrl;
         readonly string _clientId;
         readonly string _clientSecret;
@@ -39,7 +56,7 @@ public OAuthAuthenticator(
             string? scope,
             OAuthFlow? flow,
             JsonSerializerSettings serializerSettings,
-            IReadableConfiguration configuration) : base("")
+            IReadableConfiguration configuration)
         {
             _tokenUrl = tokenUrl;
             _clientId = clientId;
@@ -70,9 +87,8 @@ public OAuthAuthenticator(
         /// <summary>
         /// Creates an authentication parameter from an access token.
         /// </summary>
-        /// <param name="accessToken">Access token to create a parameter from.</param>
         /// <returns>An authentication parameter.</returns>
-        protected override async ValueTask<Parameter> GetAuthenticationParameter(string accessToken)
+        protected async ValueTask<Parameter> GetAuthenticationParameter()
         {
             var token = string.IsNullOrEmpty(Token) ? await GetToken().ConfigureAwait(false) : Token;
             return new HeaderParameter(KnownHeaders.Authorization, token);
@@ -84,31 +100,45 @@ protected override async ValueTask<Parameter> GetAuthenticationParameter(string
         /// <returns>An authentication token.</returns>
         async Task<string> GetToken()
         {
-            var client = new RestClient(_tokenUrl,
-                configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
-
-            var request = new RestRequest()
-                .AddParameter("grant_type", _grantType)
-                .AddParameter("client_id", _clientId)
-                .AddParameter("client_secret", _clientSecret);
+            var client = new RestClient(_tokenUrl, configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
 
+            var request = new RestRequest();
+            if (!string.IsNullOrWhiteSpace(_token?.RefreshToken))
+            {
+                request.AddParameter("grant_type", "refresh_token")
+                    .AddParameter("refresh_token", _token.RefreshToken);
+            }
+            else
+            {
+                request
+                    .AddParameter("grant_type", _grantType)
+                    .AddParameter("client_id", _clientId)
+                    .AddParameter("client_secret", _clientSecret);
+            }
             if (!string.IsNullOrEmpty(_scope))
             {
                 request.AddParameter("scope", _scope);
             }
-
-            var response = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
-            
+            _token = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
             // RFC6749 - token_type is case insensitive.
             // RFC6750 - In Authorization header Bearer should be capitalized.
             // Fix the capitalization irrespective of token_type casing.
-            switch (response.TokenType?.ToLower())
+            switch (_token?.TokenType?.ToLower())
             {
                 case "bearer":
-                    return $"Bearer {response.AccessToken}";
+                    return $"Bearer {_token.AccessToken}";
                 default:
-                    return $"{response.TokenType} {response.AccessToken}";
+                    return $"{_token?.TokenType} {_token?.AccessToken}";
             }
         }
+
+        /// <summary>
+        /// Retrieves the authentication token (creating a new one if necessary) and adds it to the current request
+        /// </summary>
+        /// <param name="client"></param>
+        /// <param name="request"></param>
+        /// <returns></returns>
+        public async ValueTask Authenticate(IRestClient client, RestRequest request)
+            => request.AddOrUpdateParameter(await GetAuthenticationParameter().ConfigureAwait(false));
     }
 }
diff --git a/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs b/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
index 0a94e17e1228..da4f4499b1cc 100644
--- a/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
+++ b/samples/client/petstore/csharp/restsharp/net7/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
@@ -8,6 +8,7 @@
  */
 
 
+using System;
 using Newtonsoft.Json;
 
 namespace Org.OpenAPITools.Client.Auth
@@ -18,5 +19,14 @@ class TokenResponse
         public string TokenType { get; set; }
         [JsonProperty("access_token")]
         public string AccessToken { get; set; }
+        [JsonProperty("expires_in")]
+        public int? ExpiresIn { get; set; }
+        [JsonProperty("created")]
+        public DateTime? Created { get; set; }
+
+        [JsonProperty("refresh_token")]
+        public string? RefreshToken { get; set; }
+
+        public DateTime? ExpiresAt => ExpiresIn == null ? null : Created?.AddSeconds(ExpiresIn.Value);
     }
 }
\ No newline at end of file
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
index d7fb1293b34b..6c6817ef501a 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
@@ -19,8 +19,25 @@ namespace Org.OpenAPITools.Client.Auth
     /// <summary>
     /// An authenticator for OAuth2 authentication flows
     /// </summary>
-    public class OAuthAuthenticator : AuthenticatorBase
+    public class OAuthAuthenticator : IAuthenticator
     {
+        private TokenResponse _token;
+
+        /// <summary>
+        /// Returns the current authentication token. Can return null if there is no authentication token, or it has expired.
+        /// </summary>
+        public string Token
+        {
+            get
+            {
+                if (_token == null) return null;
+                if (_token.ExpiresIn == null) return _token.AccessToken;
+                if (_token.ExpiresAt < DateTime.Now) return null;
+
+                return _token.AccessToken;
+            }
+        }
+
         readonly string _tokenUrl;
         readonly string _clientId;
         readonly string _clientSecret;
@@ -39,7 +56,7 @@ public OAuthAuthenticator(
             string scope,
             OAuthFlow? flow,
             JsonSerializerSettings serializerSettings,
-            IReadableConfiguration configuration) : base("")
+            IReadableConfiguration configuration)
         {
             _tokenUrl = tokenUrl;
             _clientId = clientId;
@@ -70,9 +87,8 @@ public OAuthAuthenticator(
         /// <summary>
         /// Creates an authentication parameter from an access token.
         /// </summary>
-        /// <param name="accessToken">Access token to create a parameter from.</param>
         /// <returns>An authentication parameter.</returns>
-        protected override async ValueTask<Parameter> GetAuthenticationParameter(string accessToken)
+        protected async ValueTask<Parameter> GetAuthenticationParameter()
         {
             var token = string.IsNullOrEmpty(Token) ? await GetToken().ConfigureAwait(false) : Token;
             return new HeaderParameter(KnownHeaders.Authorization, token);
@@ -84,31 +100,45 @@ protected override async ValueTask<Parameter> GetAuthenticationParameter(string
         /// <returns>An authentication token.</returns>
         async Task<string> GetToken()
         {
-            var client = new RestClient(_tokenUrl,
-                configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
-
-            var request = new RestRequest()
-                .AddParameter("grant_type", _grantType)
-                .AddParameter("client_id", _clientId)
-                .AddParameter("client_secret", _clientSecret);
+            var client = new RestClient(_tokenUrl, configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
 
+            var request = new RestRequest();
+            if (!string.IsNullOrWhiteSpace(_token?.RefreshToken))
+            {
+                request.AddParameter("grant_type", "refresh_token")
+                    .AddParameter("refresh_token", _token.RefreshToken);
+            }
+            else
+            {
+                request
+                    .AddParameter("grant_type", _grantType)
+                    .AddParameter("client_id", _clientId)
+                    .AddParameter("client_secret", _clientSecret);
+            }
             if (!string.IsNullOrEmpty(_scope))
             {
                 request.AddParameter("scope", _scope);
             }
-
-            var response = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
-            
+            _token = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
             // RFC6749 - token_type is case insensitive.
             // RFC6750 - In Authorization header Bearer should be capitalized.
             // Fix the capitalization irrespective of token_type casing.
-            switch (response.TokenType?.ToLower())
+            switch (_token?.TokenType?.ToLower())
             {
                 case "bearer":
-                    return $"Bearer {response.AccessToken}";
+                    return $"Bearer {_token.AccessToken}";
                 default:
-                    return $"{response.TokenType} {response.AccessToken}";
+                    return $"{_token?.TokenType} {_token?.AccessToken}";
             }
         }
+
+        /// <summary>
+        /// Retrieves the authentication token (creating a new one if necessary) and adds it to the current request
+        /// </summary>
+        /// <param name="client"></param>
+        /// <param name="request"></param>
+        /// <returns></returns>
+        public async ValueTask Authenticate(IRestClient client, RestRequest request)
+            => request.AddOrUpdateParameter(await GetAuthenticationParameter().ConfigureAwait(false));
     }
 }
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
index 0a94e17e1228..95e03c36e105 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
@@ -8,6 +8,7 @@
  */
 
 
+using System;
 using Newtonsoft.Json;
 
 namespace Org.OpenAPITools.Client.Auth
@@ -18,5 +19,14 @@ class TokenResponse
         public string TokenType { get; set; }
         [JsonProperty("access_token")]
         public string AccessToken { get; set; }
+        [JsonProperty("expires_in")]
+        public int? ExpiresIn { get; set; }
+        [JsonProperty("created")]
+        public DateTime? Created { get; set; }
+
+        [JsonProperty("refresh_token")]
+        public string RefreshToken { get; set; }
+
+        public DateTime? ExpiresAt => ExpiresIn == null ? null : Created?.AddSeconds(ExpiresIn.Value);
     }
 }
\ No newline at end of file
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
index d7fb1293b34b..6c6817ef501a 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Client/Auth/OAuthAuthenticator.cs
@@ -19,8 +19,25 @@ namespace Org.OpenAPITools.Client.Auth
     /// <summary>
     /// An authenticator for OAuth2 authentication flows
     /// </summary>
-    public class OAuthAuthenticator : AuthenticatorBase
+    public class OAuthAuthenticator : IAuthenticator
     {
+        private TokenResponse _token;
+
+        /// <summary>
+        /// Returns the current authentication token. Can return null if there is no authentication token, or it has expired.
+        /// </summary>
+        public string Token
+        {
+            get
+            {
+                if (_token == null) return null;
+                if (_token.ExpiresIn == null) return _token.AccessToken;
+                if (_token.ExpiresAt < DateTime.Now) return null;
+
+                return _token.AccessToken;
+            }
+        }
+
         readonly string _tokenUrl;
         readonly string _clientId;
         readonly string _clientSecret;
@@ -39,7 +56,7 @@ public OAuthAuthenticator(
             string scope,
             OAuthFlow? flow,
             JsonSerializerSettings serializerSettings,
-            IReadableConfiguration configuration) : base("")
+            IReadableConfiguration configuration)
         {
             _tokenUrl = tokenUrl;
             _clientId = clientId;
@@ -70,9 +87,8 @@ public OAuthAuthenticator(
         /// <summary>
         /// Creates an authentication parameter from an access token.
         /// </summary>
-        /// <param name="accessToken">Access token to create a parameter from.</param>
         /// <returns>An authentication parameter.</returns>
-        protected override async ValueTask<Parameter> GetAuthenticationParameter(string accessToken)
+        protected async ValueTask<Parameter> GetAuthenticationParameter()
         {
             var token = string.IsNullOrEmpty(Token) ? await GetToken().ConfigureAwait(false) : Token;
             return new HeaderParameter(KnownHeaders.Authorization, token);
@@ -84,31 +100,45 @@ protected override async ValueTask<Parameter> GetAuthenticationParameter(string
         /// <returns>An authentication token.</returns>
         async Task<string> GetToken()
         {
-            var client = new RestClient(_tokenUrl,
-                configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
-
-            var request = new RestRequest()
-                .AddParameter("grant_type", _grantType)
-                .AddParameter("client_id", _clientId)
-                .AddParameter("client_secret", _clientSecret);
+            var client = new RestClient(_tokenUrl, configureSerialization: serializerConfig => serializerConfig.UseSerializer(() => new CustomJsonCodec(_serializerSettings, _configuration)));
 
+            var request = new RestRequest();
+            if (!string.IsNullOrWhiteSpace(_token?.RefreshToken))
+            {
+                request.AddParameter("grant_type", "refresh_token")
+                    .AddParameter("refresh_token", _token.RefreshToken);
+            }
+            else
+            {
+                request
+                    .AddParameter("grant_type", _grantType)
+                    .AddParameter("client_id", _clientId)
+                    .AddParameter("client_secret", _clientSecret);
+            }
             if (!string.IsNullOrEmpty(_scope))
             {
                 request.AddParameter("scope", _scope);
             }
-
-            var response = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
-            
+            _token = await client.PostAsync<TokenResponse>(request).ConfigureAwait(false);
             // RFC6749 - token_type is case insensitive.
             // RFC6750 - In Authorization header Bearer should be capitalized.
             // Fix the capitalization irrespective of token_type casing.
-            switch (response.TokenType?.ToLower())
+            switch (_token?.TokenType?.ToLower())
             {
                 case "bearer":
-                    return $"Bearer {response.AccessToken}";
+                    return $"Bearer {_token.AccessToken}";
                 default:
-                    return $"{response.TokenType} {response.AccessToken}";
+                    return $"{_token?.TokenType} {_token?.AccessToken}";
             }
         }
+
+        /// <summary>
+        /// Retrieves the authentication token (creating a new one if necessary) and adds it to the current request
+        /// </summary>
+        /// <param name="client"></param>
+        /// <param name="request"></param>
+        /// <returns></returns>
+        public async ValueTask Authenticate(IRestClient client, RestRequest request)
+            => request.AddOrUpdateParameter(await GetAuthenticationParameter().ConfigureAwait(false));
     }
 }
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
index 0a94e17e1228..95e03c36e105 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Client/Auth/TokenResponse.cs
@@ -8,6 +8,7 @@
  */
 
 
+using System;
 using Newtonsoft.Json;
 
 namespace Org.OpenAPITools.Client.Auth
@@ -18,5 +19,14 @@ class TokenResponse
         public string TokenType { get; set; }
         [JsonProperty("access_token")]
         public string AccessToken { get; set; }
+        [JsonProperty("expires_in")]
+        public int? ExpiresIn { get; set; }
+        [JsonProperty("created")]
+        public DateTime? Created { get; set; }
+
+        [JsonProperty("refresh_token")]
+        public string RefreshToken { get; set; }
+
+        public DateTime? ExpiresAt => ExpiresIn == null ? null : Created?.AddSeconds(ExpiresIn.Value);
     }
 }
\ No newline at end of file