diff --git a/bin/utils/ensure-up-to-date b/bin/utils/ensure-up-to-date
index c2e38093de4..d27cfa789f6 100755
--- a/bin/utils/ensure-up-to-date
+++ b/bin/utils/ensure-up-to-date
@@ -53,6 +53,7 @@ declare -a scripts=(
 "./bin/go-petstore.sh"
 "./bin/go-gin-petstore-server.sh"
 "./bin/groovy-petstore.sh"
+"./bin/apex-petstore.sh"
 #"./bin/elm-petstore-all.sh"
 "./bin/meta-codegen.sh"
 # OTHERS
diff --git a/samples/client/petstore/apex/.openapi-generator/VERSION b/samples/client/petstore/apex/.openapi-generator/VERSION
index e24c1f857e0..06b5019af3f 100644
--- a/samples/client/petstore/apex/.openapi-generator/VERSION
+++ b/samples/client/petstore/apex/.openapi-generator/VERSION
@@ -1 +1 @@
-3.3.3-SNAPSHOT
\ No newline at end of file
+4.0.1-SNAPSHOT
\ No newline at end of file
diff --git a/samples/client/petstore/apex/force-app/main/default/classes/OASApiResponse.cls b/samples/client/petstore/apex/force-app/main/default/classes/OASApiResponse.cls
index 2cae18bc3c4..f9a93bbd3ca 100644
--- a/samples/client/petstore/apex/force-app/main/default/classes/OASApiResponse.cls
+++ b/samples/client/petstore/apex/force-app/main/default/classes/OASApiResponse.cls
@@ -2,11 +2,11 @@
  * OpenAPI Petstore
  * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
  *
- * OpenAPI spec version: 1.0.0
+ * The version of the OpenAPI document: 1.0.0
  * 
  *
  * NOTE: This class is auto generated by the OAS code generator program.
- * https://github.com/OAS-api/OAS-codegen.git
+ * https://github.com/OpenAPITools/openapi-generator
  * Do not edit the class manually.
  */
 
diff --git a/samples/client/petstore/apex/force-app/main/default/classes/OASCategory.cls b/samples/client/petstore/apex/force-app/main/default/classes/OASCategory.cls
index 69f1a5c677f..9b20682c9cd 100644
--- a/samples/client/petstore/apex/force-app/main/default/classes/OASCategory.cls
+++ b/samples/client/petstore/apex/force-app/main/default/classes/OASCategory.cls
@@ -2,11 +2,11 @@
  * OpenAPI Petstore
  * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
  *
- * OpenAPI spec version: 1.0.0
+ * The version of the OpenAPI document: 1.0.0
  * 
  *
  * NOTE: This class is auto generated by the OAS code generator program.
- * https://github.com/OAS-api/OAS-codegen.git
+ * https://github.com/OpenAPITools/openapi-generator
  * Do not edit the class manually.
  */
 
diff --git a/samples/client/petstore/apex/force-app/main/default/classes/OASOrder.cls b/samples/client/petstore/apex/force-app/main/default/classes/OASOrder.cls
index cd9e98a3e81..641462b2e6c 100644
--- a/samples/client/petstore/apex/force-app/main/default/classes/OASOrder.cls
+++ b/samples/client/petstore/apex/force-app/main/default/classes/OASOrder.cls
@@ -2,11 +2,11 @@
  * OpenAPI Petstore
  * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
  *
- * OpenAPI spec version: 1.0.0
+ * The version of the OpenAPI document: 1.0.0
  * 
  *
  * NOTE: This class is auto generated by the OAS code generator program.
- * https://github.com/OAS-api/OAS-codegen.git
+ * https://github.com/OpenAPITools/openapi-generator
  * Do not edit the class manually.
  */
 
diff --git a/samples/client/petstore/apex/force-app/main/default/classes/OASPet.cls b/samples/client/petstore/apex/force-app/main/default/classes/OASPet.cls
index 2a521f464e5..b9794447897 100644
--- a/samples/client/petstore/apex/force-app/main/default/classes/OASPet.cls
+++ b/samples/client/petstore/apex/force-app/main/default/classes/OASPet.cls
@@ -2,11 +2,11 @@
  * OpenAPI Petstore
  * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
  *
- * OpenAPI spec version: 1.0.0
+ * The version of the OpenAPI document: 1.0.0
  * 
  *
  * NOTE: This class is auto generated by the OAS code generator program.
- * https://github.com/OAS-api/OAS-codegen.git
+ * https://github.com/OpenAPITools/openapi-generator
  * Do not edit the class manually.
  */
 
diff --git a/samples/client/petstore/apex/force-app/main/default/classes/OASPetApi.cls b/samples/client/petstore/apex/force-app/main/default/classes/OASPetApi.cls
index 331cb6d2ef1..1ad41d52ab5 100644
--- a/samples/client/petstore/apex/force-app/main/default/classes/OASPetApi.cls
+++ b/samples/client/petstore/apex/force-app/main/default/classes/OASPetApi.cls
@@ -2,11 +2,11 @@
  * OpenAPI Petstore
  * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
  *
- * OpenAPI spec version: 1.0.0
+ * The version of the OpenAPI document: 1.0.0
  * 
  *
  * NOTE: This class is auto generated by the OAS code generator program.
- * https://github.com/OAS-api/OAS-codegen.git
+ * https://github.com/OpenAPITools/openapi-generator
  * Do not edit the class manually.
  */
 
@@ -28,17 +28,17 @@ public class OASPetApi {
     /**
      * Add a new pet to the store
      * 
-     * @param oaSPet Pet object that needs to be added to the store (required)
+     * @param body Pet object that needs to be added to the store (required)
      * @throws OAS.ApiException if fails to make API call
      */
     public void addPet(Map<String, Object> params) {
-        client.assertNotNull(params.get('oaSPet'), 'oaSPet');
+        client.assertNotNull(params.get('body'), 'body');
         List<OAS.Param> query = new List<OAS.Param>();
         List<OAS.Param> form = new List<OAS.Param>();
 
         client.invoke(
             'POST', '/pet',
-            (OASPet) params.get('oaSPet'),
+            (OASPet) params.get('body'),
             query, form,
             new Map<String, Object>(),
             new Map<String, Object>(),
@@ -157,17 +157,17 @@ public class OASPetApi {
     /**
      * Update an existing pet
      * 
-     * @param oaSPet Pet object that needs to be added to the store (required)
+     * @param body Pet object that needs to be added to the store (required)
      * @throws OAS.ApiException if fails to make API call
      */
     public void updatePet(Map<String, Object> params) {
-        client.assertNotNull(params.get('oaSPet'), 'oaSPet');
+        client.assertNotNull(params.get('body'), 'body');
         List<OAS.Param> query = new List<OAS.Param>();
         List<OAS.Param> form = new List<OAS.Param>();
 
         client.invoke(
             'PUT', '/pet',
-            (OASPet) params.get('oaSPet'),
+            (OASPet) params.get('body'),
             query, form,
             new Map<String, Object>(),
             new Map<String, Object>(),
diff --git a/samples/client/petstore/apex/force-app/main/default/classes/OASStoreApi.cls b/samples/client/petstore/apex/force-app/main/default/classes/OASStoreApi.cls
index 215f61329f0..c5307e79fea 100644
--- a/samples/client/petstore/apex/force-app/main/default/classes/OASStoreApi.cls
+++ b/samples/client/petstore/apex/force-app/main/default/classes/OASStoreApi.cls
@@ -2,11 +2,11 @@
  * OpenAPI Petstore
  * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
  *
- * OpenAPI spec version: 1.0.0
+ * The version of the OpenAPI document: 1.0.0
  * 
  *
  * NOTE: This class is auto generated by the OAS code generator program.
- * https://github.com/OAS-api/OAS-codegen.git
+ * https://github.com/OpenAPITools/openapi-generator
  * Do not edit the class manually.
  */
 
@@ -98,18 +98,18 @@ public class OASStoreApi {
     /**
      * Place an order for a pet
      * 
-     * @param oaSOrder order placed for purchasing the pet (required)
+     * @param body order placed for purchasing the pet (required)
      * @return OASOrder
      * @throws OAS.ApiException if fails to make API call
      */
     public OASOrder placeOrder(Map<String, Object> params) {
-        client.assertNotNull(params.get('oaSOrder'), 'oaSOrder');
+        client.assertNotNull(params.get('body'), 'body');
         List<OAS.Param> query = new List<OAS.Param>();
         List<OAS.Param> form = new List<OAS.Param>();
 
         return (OASOrder) client.invoke(
             'POST', '/store/order',
-            (OASOrder) params.get('oaSOrder'),
+            (OASOrder) params.get('body'),
             query, form,
             new Map<String, Object>(),
             new Map<String, Object>(),
diff --git a/samples/client/petstore/apex/force-app/main/default/classes/OASTag.cls b/samples/client/petstore/apex/force-app/main/default/classes/OASTag.cls
index d3658da066c..b01069d4e18 100644
--- a/samples/client/petstore/apex/force-app/main/default/classes/OASTag.cls
+++ b/samples/client/petstore/apex/force-app/main/default/classes/OASTag.cls
@@ -2,11 +2,11 @@
  * OpenAPI Petstore
  * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
  *
- * OpenAPI spec version: 1.0.0
+ * The version of the OpenAPI document: 1.0.0
  * 
  *
  * NOTE: This class is auto generated by the OAS code generator program.
- * https://github.com/OAS-api/OAS-codegen.git
+ * https://github.com/OpenAPITools/openapi-generator
  * Do not edit the class manually.
  */
 
diff --git a/samples/client/petstore/apex/force-app/main/default/classes/OASUser.cls b/samples/client/petstore/apex/force-app/main/default/classes/OASUser.cls
index 8ce543f9fe2..7fd06c6d2cb 100644
--- a/samples/client/petstore/apex/force-app/main/default/classes/OASUser.cls
+++ b/samples/client/petstore/apex/force-app/main/default/classes/OASUser.cls
@@ -2,11 +2,11 @@
  * OpenAPI Petstore
  * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
  *
- * OpenAPI spec version: 1.0.0
+ * The version of the OpenAPI document: 1.0.0
  * 
  *
  * NOTE: This class is auto generated by the OAS code generator program.
- * https://github.com/OAS-api/OAS-codegen.git
+ * https://github.com/OpenAPITools/openapi-generator
  * Do not edit the class manually.
  */
 
diff --git a/samples/client/petstore/apex/force-app/main/default/classes/OASUserApi.cls b/samples/client/petstore/apex/force-app/main/default/classes/OASUserApi.cls
index c86416a450e..79adfc28ddd 100644
--- a/samples/client/petstore/apex/force-app/main/default/classes/OASUserApi.cls
+++ b/samples/client/petstore/apex/force-app/main/default/classes/OASUserApi.cls
@@ -2,11 +2,11 @@
  * OpenAPI Petstore
  * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
  *
- * OpenAPI spec version: 1.0.0
+ * The version of the OpenAPI document: 1.0.0
  * 
  *
  * NOTE: This class is auto generated by the OAS code generator program.
- * https://github.com/OAS-api/OAS-codegen.git
+ * https://github.com/OpenAPITools/openapi-generator
  * Do not edit the class manually.
  */
 
@@ -28,17 +28,17 @@ public class OASUserApi {
     /**
      * Create user
      * This can only be done by the logged in user.
-     * @param oaSUser Created user object (required)
+     * @param body Created user object (required)
      * @throws OAS.ApiException if fails to make API call
      */
     public void createUser(Map<String, Object> params) {
-        client.assertNotNull(params.get('oaSUser'), 'oaSUser');
+        client.assertNotNull(params.get('body'), 'body');
         List<OAS.Param> query = new List<OAS.Param>();
         List<OAS.Param> form = new List<OAS.Param>();
 
         client.invoke(
             'POST', '/user',
-            (OASUser) params.get('oaSUser'),
+            (OASUser) params.get('body'),
             query, form,
             new Map<String, Object>(),
             new Map<String, Object>(),
@@ -51,17 +51,17 @@ public class OASUserApi {
     /**
      * Creates list of users with given input array
      * 
-     * @param oaSUser List of user object (required)
+     * @param body List of user object (required)
      * @throws OAS.ApiException if fails to make API call
      */
     public void createUsersWithArrayInput(Map<String, Object> params) {
-        client.assertNotNull(params.get('oaSUser'), 'oaSUser');
+        client.assertNotNull(params.get('body'), 'body');
         List<OAS.Param> query = new List<OAS.Param>();
         List<OAS.Param> form = new List<OAS.Param>();
 
         client.invoke(
             'POST', '/user/createWithArray',
-            (List<OASUser>) params.get('oaSUser'),
+            (List<OASUser>) params.get('body'),
             query, form,
             new Map<String, Object>(),
             new Map<String, Object>(),
@@ -74,17 +74,17 @@ public class OASUserApi {
     /**
      * Creates list of users with given input array
      * 
-     * @param oaSUser List of user object (required)
+     * @param body List of user object (required)
      * @throws OAS.ApiException if fails to make API call
      */
     public void createUsersWithListInput(Map<String, Object> params) {
-        client.assertNotNull(params.get('oaSUser'), 'oaSUser');
+        client.assertNotNull(params.get('body'), 'body');
         List<OAS.Param> query = new List<OAS.Param>();
         List<OAS.Param> form = new List<OAS.Param>();
 
         client.invoke(
             'POST', '/user/createWithList',
-            (List<OASUser>) params.get('oaSUser'),
+            (List<OASUser>) params.get('body'),
             query, form,
             new Map<String, Object>(),
             new Map<String, Object>(),
@@ -197,18 +197,18 @@ public class OASUserApi {
      * Updated user
      * This can only be done by the logged in user.
      * @param username name that need to be deleted (required)
-     * @param oaSUser Updated user object (required)
+     * @param body Updated user object (required)
      * @throws OAS.ApiException if fails to make API call
      */
     public void updateUser(Map<String, Object> params) {
         client.assertNotNull(params.get('username'), 'username');
-        client.assertNotNull(params.get('oaSUser'), 'oaSUser');
+        client.assertNotNull(params.get('body'), 'body');
         List<OAS.Param> query = new List<OAS.Param>();
         List<OAS.Param> form = new List<OAS.Param>();
 
         client.invoke(
             'PUT', '/user/{username}',
-            (OASUser) params.get('oaSUser'),
+            (OASUser) params.get('body'),
             query, form,
             new Map<String, Object>{
                 'username' => (String) params.get('username')