diff --git a/modules/openapi-generator/src/main/resources/python-fastapi/endpoint_argument_definition.mustache b/modules/openapi-generator/src/main/resources/python-fastapi/endpoint_argument_definition.mustache
index 706b648e0151..3b7dc9e30cc8 100644
--- a/modules/openapi-generator/src/main/resources/python-fastapi/endpoint_argument_definition.mustache
+++ b/modules/openapi-generator/src/main/resources/python-fastapi/endpoint_argument_definition.mustache
@@ -1 +1 @@
-{{#isPathParam}}{{baseName}}{{/isPathParam}}{{^isPathParam}}{{paramName}}{{/isPathParam}}: {{>param_type}} = {{#isPathParam}}Path{{/isPathParam}}{{#isHeaderParam}}Header{{/isHeaderParam}}{{#isFormParam}}Form{{/isFormParam}}{{#isQueryParam}}Query{{/isQueryParam}}{{#isCookieParam}}Cookie{{/isCookieParam}}{{#isBodyParam}}Body{{/isBodyParam}}({{&defaultValue}}{{^defaultValue}}{{#isPathParam}}...{{/isPathParam}}{{^isPathParam}}None{{/isPathParam}}{{/defaultValue}}, description="{{description}}"{{#isQueryParam}}, alias="{{baseName}}"{{/isQueryParam}}{{#isLong}}{{#minimum}}, ge={{.}}{{/minimum}}{{#maximum}}, le={{.}}{{/maximum}}{{/isLong}}{{#isInteger}}{{#minimum}}, ge={{.}}{{/minimum}}{{#maximum}}, le={{.}}{{/maximum}}{{/isInteger}}{{#vendorExtensions.x-regex}}, regex=r"{{.}}"{{/vendorExtensions.x-regex}}{{#minLength}}, min_length={{.}}{{/minLength}}{{#maxLength}}, max_length={{.}}{{/maxLength}})
\ No newline at end of file
+{{#isPathParam}}{{baseName}}{{/isPathParam}}{{^isPathParam}}{{paramName}}{{/isPathParam}}: {{>param_type}} = {{#isPathParam}}Path{{/isPathParam}}{{#isHeaderParam}}Header{{/isHeaderParam}}{{#isFormParam}}Form{{/isFormParam}}{{#isQueryParam}}Query{{/isQueryParam}}{{#isCookieParam}}Cookie{{/isCookieParam}}{{#isBodyParam}}Body{{/isBodyParam}}({{&defaultValue}}{{^defaultValue}}{{#required}}...{{/required}}{{^required}}None{{/required}}{{/defaultValue}}, description="{{description}}"{{#isQueryParam}}, alias="{{baseName}}"{{/isQueryParam}}{{#isLong}}{{#minimum}}, ge={{.}}{{/minimum}}{{#maximum}}, le={{.}}{{/maximum}}{{/isLong}}{{#isInteger}}{{#minimum}}, ge={{.}}{{/minimum}}{{#maximum}}, le={{.}}{{/maximum}}{{/isInteger}}{{#vendorExtensions.x-regex}}, regex=r"{{.}}"{{/vendorExtensions.x-regex}}{{#minLength}}, min_length={{.}}{{/minLength}}{{#maxLength}}, max_length={{.}}{{/maxLength}})
diff --git a/samples/server/petstore/python-fastapi/src/openapi_server/apis/fake_api.py b/samples/server/petstore/python-fastapi/src/openapi_server/apis/fake_api.py
index 0e3f8d51b319..966ef8084147 100644
--- a/samples/server/petstore/python-fastapi/src/openapi_server/apis/fake_api.py
+++ b/samples/server/petstore/python-fastapi/src/openapi_server/apis/fake_api.py
@@ -46,8 +46,10 @@
     response_model_by_alias=True,
 )
 async def fake_query_param_default(
-    has_default: Annotated[Optional[StrictStr], Field(description="has default value")] = Query('Hello World', description="has default value", alias="hasDefault"),
-    no_default: Annotated[Optional[StrictStr], Field(description="no default value")] = Query(None, description="no default value", alias="noDefault"),
+    has_default: Annotated[Optional[StrictStr], Field(description="has default value")] = Query('Hello World', description="has default value", alias="hasDefault")
+,
+    no_default: Annotated[Optional[StrictStr], Field(description="no default value")] = Query(None, description="no default value", alias="noDefault")
+,
 ) -> None:
     """"""
     if not BaseFakeApi.subclasses:
diff --git a/samples/server/petstore/python-fastapi/src/openapi_server/apis/pet_api.py b/samples/server/petstore/python-fastapi/src/openapi_server/apis/pet_api.py
index 416272bcd61d..94c5be7964a0 100644
--- a/samples/server/petstore/python-fastapi/src/openapi_server/apis/pet_api.py
+++ b/samples/server/petstore/python-fastapi/src/openapi_server/apis/pet_api.py
@@ -50,7 +50,8 @@
     response_model_by_alias=True,
 )
 async def update_pet(
-    pet: Annotated[Pet, Field(description="Pet object that needs to be added to the store")] = Body(None, description="Pet object that needs to be added to the store"),
+    pet: Annotated[Pet, Field(description="Pet object that needs to be added to the store")] = Body(..., description="Pet object that needs to be added to the store")
+,
     token_petstore_auth: TokenModel = Security(
         get_token_petstore_auth, scopes=["write:pets", "read:pets"]
     ),
@@ -72,7 +73,8 @@ async def update_pet(
     response_model_by_alias=True,
 )
 async def add_pet(
-    pet: Annotated[Pet, Field(description="Pet object that needs to be added to the store")] = Body(None, description="Pet object that needs to be added to the store"),
+    pet: Annotated[Pet, Field(description="Pet object that needs to be added to the store")] = Body(..., description="Pet object that needs to be added to the store")
+,
     token_petstore_auth: TokenModel = Security(
         get_token_petstore_auth, scopes=["write:pets", "read:pets"]
     ),
@@ -94,7 +96,8 @@ async def add_pet(
     response_model_by_alias=True,
 )
 async def find_pets_by_status(
-    status: Annotated[List[StrictStr], Field(description="Status values that need to be considered for filter")] = Query(None, description="Status values that need to be considered for filter", alias="status"),
+    status: Annotated[List[StrictStr], Field(description="Status values that need to be considered for filter")] = Query(..., description="Status values that need to be considered for filter", alias="status")
+,
     token_petstore_auth: TokenModel = Security(
         get_token_petstore_auth, scopes=["read:pets"]
     ),
@@ -116,7 +119,8 @@ async def find_pets_by_status(
     response_model_by_alias=True,
 )
 async def find_pets_by_tags(
-    tags: Annotated[List[StrictStr], Field(description="Tags to filter by")] = Query(None, description="Tags to filter by", alias="tags"),
+    tags: Annotated[List[StrictStr], Field(description="Tags to filter by")] = Query(..., description="Tags to filter by", alias="tags")
+,
     token_petstore_auth: TokenModel = Security(
         get_token_petstore_auth, scopes=["read:pets"]
     ),
@@ -139,7 +143,8 @@ async def find_pets_by_tags(
     response_model_by_alias=True,
 )
 async def get_pet_by_id(
-    petId: Annotated[StrictInt, Field(description="ID of pet to return")] = Path(..., description="ID of pet to return"),
+    petId: Annotated[StrictInt, Field(description="ID of pet to return")] = Path(..., description="ID of pet to return")
+,
     token_api_key: TokenModel = Security(
         get_token_api_key
     ),
@@ -160,9 +165,12 @@ async def get_pet_by_id(
     response_model_by_alias=True,
 )
 async def update_pet_with_form(
-    petId: Annotated[StrictInt, Field(description="ID of pet that needs to be updated")] = Path(..., description="ID of pet that needs to be updated"),
-    name: Annotated[Optional[StrictStr], Field(description="Updated name of the pet")] = Form(None, description="Updated name of the pet"),
-    status: Annotated[Optional[StrictStr], Field(description="Updated status of the pet")] = Form(None, description="Updated status of the pet"),
+    petId: Annotated[StrictInt, Field(description="ID of pet that needs to be updated")] = Path(..., description="ID of pet that needs to be updated")
+,
+    name: Annotated[Optional[StrictStr], Field(description="Updated name of the pet")] = Form(None, description="Updated name of the pet")
+,
+    status: Annotated[Optional[StrictStr], Field(description="Updated status of the pet")] = Form(None, description="Updated status of the pet")
+,
     token_petstore_auth: TokenModel = Security(
         get_token_petstore_auth, scopes=["write:pets", "read:pets"]
     ),
@@ -183,8 +191,10 @@ async def update_pet_with_form(
     response_model_by_alias=True,
 )
 async def delete_pet(
-    petId: Annotated[StrictInt, Field(description="Pet id to delete")] = Path(..., description="Pet id to delete"),
-    api_key: Optional[StrictStr] = Header(None, description=""),
+    petId: Annotated[StrictInt, Field(description="Pet id to delete")] = Path(..., description="Pet id to delete")
+,
+    api_key: Optional[StrictStr] = Header(None, description="")
+,
     token_petstore_auth: TokenModel = Security(
         get_token_petstore_auth, scopes=["write:pets", "read:pets"]
     ),
@@ -205,9 +215,12 @@ async def delete_pet(
     response_model_by_alias=True,
 )
 async def upload_file(
-    petId: Annotated[StrictInt, Field(description="ID of pet to update")] = Path(..., description="ID of pet to update"),
-    additional_metadata: Annotated[Optional[StrictStr], Field(description="Additional data to pass to server")] = Form(None, description="Additional data to pass to server"),
-    file: Annotated[Optional[Union[StrictBytes, StrictStr, Tuple[StrictStr, StrictBytes]]], Field(description="file to upload")] = Form(None, description="file to upload"),
+    petId: Annotated[StrictInt, Field(description="ID of pet to update")] = Path(..., description="ID of pet to update")
+,
+    additional_metadata: Annotated[Optional[StrictStr], Field(description="Additional data to pass to server")] = Form(None, description="Additional data to pass to server")
+,
+    file: Annotated[Optional[Union[StrictBytes, StrictStr, Tuple[StrictStr, StrictBytes]]], Field(description="file to upload")] = Form(None, description="file to upload")
+,
     token_petstore_auth: TokenModel = Security(
         get_token_petstore_auth, scopes=["write:pets", "read:pets"]
     ),
diff --git a/samples/server/petstore/python-fastapi/src/openapi_server/apis/store_api.py b/samples/server/petstore/python-fastapi/src/openapi_server/apis/store_api.py
index 3d2744c2e028..6dbefdcaa1a9 100644
--- a/samples/server/petstore/python-fastapi/src/openapi_server/apis/store_api.py
+++ b/samples/server/petstore/python-fastapi/src/openapi_server/apis/store_api.py
@@ -67,7 +67,8 @@ async def get_inventory(
     response_model_by_alias=True,
 )
 async def place_order(
-    order: Annotated[Order, Field(description="order placed for purchasing the pet")] = Body(None, description="order placed for purchasing the pet"),
+    order: Annotated[Order, Field(description="order placed for purchasing the pet")] = Body(..., description="order placed for purchasing the pet")
+,
 ) -> Order:
     """"""
     if not BaseStoreApi.subclasses:
@@ -87,7 +88,8 @@ async def place_order(
     response_model_by_alias=True,
 )
 async def get_order_by_id(
-    orderId: Annotated[int, Field(le=5, strict=True, ge=1, description="ID of pet that needs to be fetched")] = Path(..., description="ID of pet that needs to be fetched", ge=1, le=5),
+    orderId: Annotated[int, Field(le=5, strict=True, ge=1, description="ID of pet that needs to be fetched")] = Path(..., description="ID of pet that needs to be fetched", ge=1, le=5)
+,
 ) -> Order:
     """For valid response try integer IDs with value <= 5 or > 10. Other values will generate exceptions"""
     if not BaseStoreApi.subclasses:
@@ -106,7 +108,8 @@ async def get_order_by_id(
     response_model_by_alias=True,
 )
 async def delete_order(
-    orderId: Annotated[StrictStr, Field(description="ID of the order that needs to be deleted")] = Path(..., description="ID of the order that needs to be deleted"),
+    orderId: Annotated[StrictStr, Field(description="ID of the order that needs to be deleted")] = Path(..., description="ID of the order that needs to be deleted")
+,
 ) -> None:
     """For valid response try integer IDs with value < 1000. Anything above 1000 or nonintegers will generate API errors"""
     if not BaseStoreApi.subclasses:
diff --git a/samples/server/petstore/python-fastapi/src/openapi_server/apis/user_api.py b/samples/server/petstore/python-fastapi/src/openapi_server/apis/user_api.py
index e7d5ea8011b5..06634461bfa4 100644
--- a/samples/server/petstore/python-fastapi/src/openapi_server/apis/user_api.py
+++ b/samples/server/petstore/python-fastapi/src/openapi_server/apis/user_api.py
@@ -46,7 +46,8 @@
     response_model_by_alias=True,
 )
 async def create_user(
-    user: Annotated[User, Field(description="Created user object")] = Body(None, description="Created user object"),
+    user: Annotated[User, Field(description="Created user object")] = Body(..., description="Created user object")
+,
     token_api_key: TokenModel = Security(
         get_token_api_key
     ),
@@ -67,7 +68,8 @@ async def create_user(
     response_model_by_alias=True,
 )
 async def create_users_with_array_input(
-    user: Annotated[List[User], Field(description="List of user object")] = Body(None, description="List of user object"),
+    user: Annotated[List[User], Field(description="List of user object")] = Body(..., description="List of user object")
+,
     token_api_key: TokenModel = Security(
         get_token_api_key
     ),
@@ -88,7 +90,8 @@ async def create_users_with_array_input(
     response_model_by_alias=True,
 )
 async def create_users_with_list_input(
-    user: Annotated[List[User], Field(description="List of user object")] = Body(None, description="List of user object"),
+    user: Annotated[List[User], Field(description="List of user object")] = Body(..., description="List of user object")
+,
     token_api_key: TokenModel = Security(
         get_token_api_key
     ),
@@ -110,8 +113,10 @@ async def create_users_with_list_input(
     response_model_by_alias=True,
 )
 async def login_user(
-    username: Annotated[str, Field(strict=True, description="The user name for login")] = Query(None, description="The user name for login", alias="username", regex=r"^[a-zA-Z0-9]+[a-zA-Z0-9\.\-_]*[a-zA-Z0-9]+$"),
-    password: Annotated[StrictStr, Field(description="The password for login in clear text")] = Query(None, description="The password for login in clear text", alias="password"),
+    username: Annotated[str, Field(strict=True, description="The user name for login")] = Query(..., description="The user name for login", alias="username", regex=r"^[a-zA-Z0-9]+[a-zA-Z0-9\.\-_]*[a-zA-Z0-9]+$")
+,
+    password: Annotated[StrictStr, Field(description="The password for login in clear text")] = Query(..., description="The password for login in clear text", alias="password")
+,
 ) -> str:
     """"""
     if not BaseUserApi.subclasses:
@@ -151,7 +156,8 @@ async def logout_user(
     response_model_by_alias=True,
 )
 async def get_user_by_name(
-    username: Annotated[StrictStr, Field(description="The name that needs to be fetched. Use user1 for testing.")] = Path(..., description="The name that needs to be fetched. Use user1 for testing."),
+    username: Annotated[StrictStr, Field(description="The name that needs to be fetched. Use user1 for testing.")] = Path(..., description="The name that needs to be fetched. Use user1 for testing.")
+,
 ) -> User:
     """"""
     if not BaseUserApi.subclasses:
@@ -170,8 +176,10 @@ async def get_user_by_name(
     response_model_by_alias=True,
 )
 async def update_user(
-    username: Annotated[StrictStr, Field(description="name that need to be deleted")] = Path(..., description="name that need to be deleted"),
-    user: Annotated[User, Field(description="Updated user object")] = Body(None, description="Updated user object"),
+    username: Annotated[StrictStr, Field(description="name that need to be deleted")] = Path(..., description="name that need to be deleted")
+,
+    user: Annotated[User, Field(description="Updated user object")] = Body(..., description="Updated user object")
+,
     token_api_key: TokenModel = Security(
         get_token_api_key
     ),
@@ -193,7 +201,8 @@ async def update_user(
     response_model_by_alias=True,
 )
 async def delete_user(
-    username: Annotated[StrictStr, Field(description="The name that needs to be deleted")] = Path(..., description="The name that needs to be deleted"),
+    username: Annotated[StrictStr, Field(description="The name that needs to be deleted")] = Path(..., description="The name that needs to be deleted")
+,
     token_api_key: TokenModel = Security(
         get_token_api_key
     ),