diff --git a/autorest/codegen/models/parameter.py b/autorest/codegen/models/parameter.py
index 8930373629b..db9ceacafc3 100644
--- a/autorest/codegen/models/parameter.py
+++ b/autorest/codegen/models/parameter.py
@@ -94,6 +94,20 @@ def constant(self) -> bool:
             return False
         return self.required
 
+    @property
+    def constant_declaration(self) -> str:
+        if self.schema:
+            if isinstance(self.schema, ConstantSchema):
+                return self.schema.get_declaration(self.schema.value)
+            raise ValueError(
+                "Trying to get constant declaration for a schema that is not ConstantSchema"
+                )
+        raise ValueError("Trying to get a declaration for a schema that doesn't exist")
+
+    @property
+    def xml_serialization_ctxt(self) -> str:
+        return self.schema.xml_serialization_ctxt() or ""
+
     @property
     def in_method_signature(self) -> bool:
         return not(
@@ -153,6 +167,10 @@ def default_value(self) -> Optional[Any]:
         # default values we bubble up from the schema
         return self._default_value()[0]
 
+    @property
+    def serialization_type(self) -> str:
+        return self.schema.serialization_type
+
     @property
     def docstring_type(self) -> str:
         return self.multiple_media_types_docstring_type or self.schema.docstring_type
diff --git a/autorest/codegen/models/property.py b/autorest/codegen/models/property.py
index bc2b57db020..055e7f4008a 100644
--- a/autorest/codegen/models/property.py
+++ b/autorest/codegen/models/property.py
@@ -76,6 +76,26 @@ def from_yaml(cls, yaml_data: Dict[str, Any], **kwargs) -> "Property":
             flattened_names=yaml_data.get("flattenedNames", []),
         )
 
+    @property
+    def constant_declaration(self) -> str:
+        if self.schema:
+            if isinstance(self.schema, ConstantSchema):
+                return self.schema.get_declaration(self.schema.value)
+            raise ValueError(
+                "Trying to get constant declaration for a schema that is not ConstantSchema"
+                )
+        raise ValueError("Trying to get a declaration for a schema that doesn't exist")
+
+    @property
+    def serialization_type(self) -> str:
+        return self.schema.serialization_type
+
+    @property
+    def xml_metadata(self) -> str:
+        if self.schema.has_xml_serialization_ctxt:
+            return f", 'xml': {{{self.schema.xml_serialization_ctxt()}}}"
+        return ""
+
     @property
     def type_annotation(self) -> str:
         if self.required:
diff --git a/autorest/codegen/models/schema_response.py b/autorest/codegen/models/schema_response.py
index bb549711781..25aba13227b 100644
--- a/autorest/codegen/models/schema_response.py
+++ b/autorest/codegen/models/schema_response.py
@@ -3,10 +3,11 @@
 # Licensed under the MIT License. See License.txt in the project root for
 # license information.
 # --------------------------------------------------------------------------
-from typing import Dict, Optional, List, Union, Any
+from typing import Dict, Optional, List, Union, Any, cast
 
 from .base_model import BaseModel
 from .base_schema import BaseSchema
+from .object_schema import ObjectSchema
 
 
 class HeaderResponse:
@@ -14,6 +15,10 @@ def __init__(self, name: str, schema) -> None:
         self.name = name
         self.schema = schema
 
+    @property
+    def serialization_type(self) -> str:
+        return self.schema.serialization_type
+
 
 class SchemaResponse(BaseModel):
     def __init__(
@@ -31,6 +36,7 @@ def __init__(
         self.status_codes = status_codes
         self.headers = headers
         self.binary = binary
+        self.nullable = self.yaml_data.get("nullable", False)
 
     @property
     def has_body(self) -> bool:
@@ -44,11 +50,47 @@ def has_headers(self) -> bool:
         """
         return bool(self.headers)
 
+    @property
+    def serialization_type(self) -> str:
+        if self.schema:
+            return self.schema.serialization_type
+        return "None"
+
+    @property
+    def operation_type_annotation(self) -> str:
+        if not self.schema:
+            return "None"
+        if self.nullable:
+            return f"Optional[{self.schema.operation_type_annotation}]"
+        return self.schema.operation_type_annotation
+
+    @property
+    def docstring_text(self) -> str:
+        if not self.schema:
+            return "None"
+        if self.nullable:
+            return f"{self.schema.docstring_text} or None"
+        return self.schema.docstring_text
+
+    @property
+    def docstring_type(self) -> str:
+        if not self.schema:
+            return "None"
+        if self.nullable:
+            return f"{self.schema.docstring_type} or None"
+        return self.schema.docstring_type
+
     @property
     def is_stream_response(self) -> bool:
         """Is the response expected to be streamable, like a download."""
         return self.binary
 
+    @property
+    def is_exception(self) -> bool:
+        if self.schema:
+            return cast(ObjectSchema, self.schema).is_exception
+        return False
+
     @classmethod
     def from_yaml(cls, yaml_data: Dict[str, Any]) -> "SchemaResponse":
 
diff --git a/autorest/codegen/templates/config.py.jinja2 b/autorest/codegen/templates/config.py.jinja2
index 57a87a87a9f..b8b45964104 100644
--- a/autorest/codegen/templates/config.py.jinja2
+++ b/autorest/codegen/templates/config.py.jinja2
@@ -35,7 +35,7 @@ class {{ code_model.class_name }}Configuration(Configuration):
 {% endif %}
 {% for parameter in code_model.global_parameters.method %}
     :param {{ parameter.serialized_name }}: {{ parameter.description }}
-    :type {{ parameter.serialized_name }}: {{ parameter.schema.docstring_type }}
+    :type {{ parameter.serialized_name }}: {{ parameter.docstring_type }}
 {% endfor %}
     """
 
@@ -54,7 +54,7 @@ class {{ code_model.class_name }}Configuration(Configuration):
 {% endfor %}
 {% if code_model.global_parameters.constant %}
     {% for constant_parameter in code_model.global_parameters.constant %}
-        self.{{ constant_parameter.serialized_name }} = {{ constant_parameter.schema.get_declaration(constant_parameter.schema.value) }}
+        self.{{ constant_parameter.serialized_name }} = {{ constant_parameter.constant_declaration }}
     {% endfor %}
 {% endif %}
 {% if code_model.options['credential_scopes'] is not none %}
diff --git a/autorest/codegen/templates/lro_operation.py.jinja2 b/autorest/codegen/templates/lro_operation.py.jinja2
index 9be6ac74e52..bcc05aafa6a 100644
--- a/autorest/codegen/templates/lro_operation.py.jinja2
+++ b/autorest/codegen/templates/lro_operation.py.jinja2
@@ -3,12 +3,12 @@
 {% set trace_decorator = "@distributed_trace_async" if async_mode else "@distributed_trace" %}
 {% set operation_name = "begin_"+operation.python_name %}
 {% macro return_docstring(async_mode) %}
-:return: An instance of {{ "Async" if async_mode }}LROPoller that returns either {{ operation.responses[0].schema.docstring_text if operation.responses[0].has_body else "None"}} or the result of cls(response)
-:rtype: ~azure.core.polling.{{ "Async" if async_mode }}LROPoller[{{ operation.responses[0].schema.docstring_type if operation.responses[0].has_body else "None" }}]{% endmacro %}
+:return: An instance of {{ "Async" if async_mode }}LROPoller that returns either {{ operation.responses[0].docstring_text }} or the result of cls(response)
+:rtype: ~azure.core.polling.{{ "Async" if async_mode }}LROPoller[{{ operation.responses[0].docstring_type }}]{% endmacro %}
 {% macro response_headers(response) %}
 response_headers = {
     {% for response_header in response.headers %}
-    '{{ response_header.name }}': self._deserialize('{{ response_header.schema.serialization_type }}', response.headers.get('{{ response_header.name }}')),
+    '{{ response_header.name }}': self._deserialize('{{ response_header.serialization_type }}', response.headers.get('{{ response_header.name }}')),
     {% endfor %}
 }
 {% endmacro %}
diff --git a/autorest/codegen/templates/lro_operation_helper.jinja2 b/autorest/codegen/templates/lro_operation_helper.jinja2
index d7d3b087dd6..a51c10d1b6f 100644
--- a/autorest/codegen/templates/lro_operation_helper.jinja2
+++ b/autorest/codegen/templates/lro_operation_helper.jinja2
@@ -18,7 +18,7 @@
 {%- for doc_string in param_documentation_string(parameter).replace('\n', '\n ').split('\n') %}
 {{ doc_string | wordwrap(width=95, break_long_words=False, wrapstring='\n ')}}
 {% endfor %}
-:type {{ parameter.serialized_name }}: {{ parameter.schema.docstring_type }}
+:type {{ parameter.serialized_name }}: {{ parameter.docstring_type }}
 {% endfor %}
 :keyword callable cls: A custom type or function that will be passed the direct response
 :keyword str continuation_token: A continuation token to restart a poller from a saved state.
diff --git a/autorest/codegen/templates/lro_paging_operation.py.jinja2 b/autorest/codegen/templates/lro_paging_operation.py.jinja2
index dd65f969181..d0bc31a1146 100644
--- a/autorest/codegen/templates/lro_paging_operation.py.jinja2
+++ b/autorest/codegen/templates/lro_paging_operation.py.jinja2
@@ -5,8 +5,8 @@
 {% set trace_decorator = "@distributed_trace_async" if async_mode else "@distributed_trace" %}
 {% set operation_name = "begin_"+operation.python_name %}
 {% macro return_docstring(async_mode) %}
-:return: An instance of {{ "Async" if async_mode }}LROPoller that returns an iterator like instance of either {{ operation.responses[0].schema.docstring_text if operation.responses[0].has_body else "None"}} or the result of cls(response)
-:rtype: ~azure.core.polling.{{ "Async" if async_mode }}LROPoller[~azure.core.{{ "async_" if async_mode else "" }}paging.{{ "Async" if async_mode }}ItemPaged[{{ operation.responses[0].schema.docstring_type if operation.responses[0].has_body else "None" }}]]{% endmacro %}
+:return: An instance of {{ "Async" if async_mode }}LROPoller that returns an iterator like instance of either {{ operation.responses[0].docstring_text }} or the result of cls(response)
+:rtype: ~azure.core.polling.{{ "Async" if async_mode }}LROPoller[~azure.core.{{ "async_" if async_mode else "" }}paging.{{ "Async" if async_mode }}ItemPaged[{{ operation.responses[0].docstring_type }}]]{% endmacro %}
 {% macro operation_docstring(async_mode) %}
 {{ lro_helper.operation_docstring_helper(operation, async_mode) }}
 {{ return_docstring(async_mode) }}
diff --git a/autorest/codegen/templates/metadata.json.jinja2 b/autorest/codegen/templates/metadata.json.jinja2
index 6be1c073bf0..3d8b841a52a 100644
--- a/autorest/codegen/templates/metadata.json.jinja2
+++ b/autorest/codegen/templates/metadata.json.jinja2
@@ -19,7 +19,7 @@
             {{ gp.serialized_name | tojson }}: {
                 "method_signature": {{ gp.sync_method_signature | tojson }},
                 "description": {{ gp.description | tojson }},
-                "docstring_type": {{ gp.schema.docstring_type | tojson }},
+                "docstring_type": {{ gp.docstring_type | tojson }},
                 "required": {{ gp.required | tojson }}
             }{{ "," if not loop.last else "" }}
             {% endfor %}
@@ -29,7 +29,7 @@
             {{ gp.serialized_name | tojson }}: {
                 "method_signature": {{ gp.sync_method_signature | tojson }},
                 "description": {{ gp.description | tojson }},
-                "docstring_type": {{ gp.schema.docstring_type | tojson }},
+                "docstring_type": {{ gp.docstring_type | tojson }},
                 "required": {{ gp.required | tojson }}
             }{{ "," if not loop.last else "" }}
             {% endfor %}
@@ -37,7 +37,7 @@
         "constant": {
             {% for gp in code_model.global_parameters.constant %}
             {% if gp.serialized_name != "api_version" %}
-            {{ gp.serialized_name | tojson }}: {{ gp.schema.get_declaration(gp.schema.value) | tojson }}{{ "," if not loop.last else "" }}
+            {{ gp.serialized_name | tojson }}: {{ gp.constant_declaration | tojson }}{{ "," if not loop.last else "" }}
             {% endif %}
             {% endfor %}
         },
diff --git a/autorest/codegen/templates/model.py.jinja2 b/autorest/codegen/templates/model.py.jinja2
index 337d7b0d7dd..eb7a156f3f5 100644
--- a/autorest/codegen/templates/model.py.jinja2
+++ b/autorest/codegen/templates/model.py.jinja2
@@ -43,8 +43,7 @@ class {{ model.name }}(msrest.serialization.Model):
     _attribute_map = {
         {% if model.properties != None %}
             {% for p in model.properties %}
-        {% set xml_metadata = (", 'xml': {" + p.schema.xml_serialization_ctxt() + "}") if p.schema.has_xml_serialization_ctxt else "" %}
-        '{{ p.name }}': {'key': '{{ p.escaped_swagger_name }}', 'type': '{{ p.schema.serialization_type}}'{{ xml_metadata }}},
+        '{{ p.name }}': {'key': '{{ p.escaped_swagger_name }}', 'type': '{{ p.serialization_type}}'{{ p.xml_metadata }}},
             {% endfor %}
         {% else%}
         {% endif %}
@@ -63,7 +62,7 @@ class {{ model.name }}(msrest.serialization.Model):
     {% if (model.properties | selectattr('constant') | first) is defined %}
 
         {% for p in model.properties | selectattr('constant')%}
-    {{ p.name }} = {{ p.schema.get_declaration(p.schema.value) }}
+    {{ p.name }} = {{ p.constant_declaration }}
         {% endfor %}
     {% endif %}
 
diff --git a/autorest/codegen/templates/operation.py.jinja2 b/autorest/codegen/templates/operation.py.jinja2
index b8006e11e2e..09240241772 100644
--- a/autorest/codegen/templates/operation.py.jinja2
+++ b/autorest/codegen/templates/operation.py.jinja2
@@ -11,8 +11,8 @@
 :rtype: {{ return_type }}
 {%- else -%}
     {% if operation.responses | selectattr('has_body') | first %}
-:return: {{ operation.responses|selectattr('has_body')|map(attribute='schema')| map(attribute='docstring_text')|unique|join(' or ') }}, or the result of cls(response)
-:rtype: {{ operation.responses|selectattr('has_body')|map(attribute='schema')| map(attribute='docstring_type')|unique|join(' or ') }}{{ " or None" if operation.has_optional_return_type }}
+:return: {{ operation.responses|selectattr('has_body')|map(attribute='docstring_text')|unique|join(' or ') }}, or the result of cls(response)
+:rtype: {{ operation.responses|selectattr('has_body')| map(attribute='docstring_type')|unique|join(' or ') }}{{ " or None" if operation.has_optional_return_type }}
     {%- else %}
 :return: None, or the result of cls(response)
 :rtype: None
@@ -39,7 +39,7 @@
 {% endfor %}
 {% if (operation.requests | length) > 1 %}
 {% set content_type_constant = operation.parameters.constant|selectattr("implementation", "equalto", "Method")|selectattr("original_parameter", "equalto", None)|selectattr("in_method_code") | selectattr("serialized_name", "equalto", "content_type") | first  %}
-:keyword str content_type: Media type of the body sent to the API. Default value is {{ content_type_constant.schema.get_declaration(content_type_constant.schema.value) }}.
+:keyword str content_type: Media type of the body sent to the API. Default value is {{ content_type_constant.constant_declaration }}.
  Allowed values are: "{{ operation.requests | map(attribute="media_types") | sum(start = []) | unique | list | join ('", "')  }}".
 {% endif %}
 :keyword callable cls: A custom type or function that will be passed the direct response
@@ -72,9 +72,9 @@
 {% if operation.parameters.constant|selectattr("implementation", "equalto", "Method")|selectattr("original_parameter", "equalto", None)|selectattr("in_method_code") %}
     {% for constant_parameter in operation.parameters.constant|selectattr("implementation", "equalto", "Method")|selectattr("original_parameter", "equalto", None)|selectattr("in_method_code") %}
     {% if constant_parameter.serialized_name == "content_type" %}
-    content_type = kwargs.pop("content_type", {{ constant_parameter.schema.get_declaration(constant_parameter.schema.value) }})
+    content_type = kwargs.pop("content_type", {{ constant_parameter.constant_declaration }})
     {% else %}
-    {{ constant_parameter.serialized_name }} = {{ constant_parameter.schema.get_declaration(constant_parameter.schema.value) }}
+    {{ constant_parameter.serialized_name }} = {{ constant_parameter.constant_declaration }}
     {% endif %}
     {% endfor %}
 {% endif %}
diff --git a/autorest/codegen/templates/operation_tools.jinja2 b/autorest/codegen/templates/operation_tools.jinja2
index ae2fd840864..305fc818d3c 100644
--- a/autorest/codegen/templates/operation_tools.jinja2
+++ b/autorest/codegen/templates/operation_tools.jinja2
@@ -2,9 +2,9 @@
 {%- if return_type -%}
 {{ return_type }}
 {%- else -%}
-{{ ((return_type_wrapper | join("[") + "[") if return_type_wrapper else "") ~ ("Optional[" if operation.has_optional_return_type else "" ) ~ ("Union[" if operation.responses | selectattr('has_body') | map(attribute='schema') | map(attribute='operation_type_annotation') | unique | list  | length > 1 else "") ~
-(operation.responses | selectattr('has_body') | map(attribute='schema') | map(attribute='operation_type_annotation') | unique | join(', ')) ~
-("]" if operation.responses | selectattr('has_body') | map(attribute='schema') | map(attribute='operation_type_annotation')| unique | list | length > 1 else "") ~ ("]" if operation.has_optional_return_type else "") ~ ( ("]" * return_type_wrapper | count ) if return_type_wrapper else "")
+{{ ((return_type_wrapper | join("[") + "[") if return_type_wrapper else "") ~ ("Optional[" if operation.has_optional_return_type else "" ) ~ ("Union[" if operation.responses | selectattr('has_body') | map(attribute='operation_type_annotation') | unique | list  | length > 1 else "") ~
+(operation.responses | selectattr('has_body') | map(attribute='operation_type_annotation') | unique | join(', ')) ~
+("]" if operation.responses | selectattr('has_body') | map(attribute='operation_type_annotation')| unique | list | length > 1 else "") ~ ("]" if operation.has_optional_return_type else "") ~ ( ("]" * return_type_wrapper | count ) if return_type_wrapper else "")
 if operation.responses | selectattr('has_body') | first
 else ((return_type_wrapper | join("[") + "[") if return_type_wrapper else "") ~ ("Optional[" if operation.has_optional_return_type else "" ) ~ "None" ~ ("]" if operation.has_optional_return_type else "") ~ ( ("]" * return_type_wrapper | count ) if return_type_wrapper else "") }}{%- endif -%}{% endmacro %}
 {# get async mypy typing #}
@@ -47,7 +47,7 @@ error_map = {
     {% endif %}
 {% for excep in operation.status_code_exceptions %}
     {% for status_code in excep.status_codes %}
-    {% set error_model = ", model=self._deserialize(models." + excep.schema.serialization_type + ", response)" if excep.schema.is_exception else "" %}
+    {% set error_model = ", model=self._deserialize(models." + excep.serialization_type + ", response)" if excep.is_exception else "" %}
     {% set error_format = ", error_format=ARMErrorFormat" if code_model.options['azure_arm'] else "" %}
     {% if status_code == 401 %}
     401: lambda response: ClientAuthenticationError(response=response{{ error_model }}{{ error_format }}),
@@ -74,13 +74,13 @@ error_map.update(kwargs.pop('error_map', {})){%- endmacro -%}
 {% macro response_handling(response) %}
   {% if response.headers %}
     {% for response_header in response.headers %}
-response_headers['{{ response_header.name }}']=self._deserialize('{{ response_header.schema.serialization_type }}', response.headers.get('{{ response_header.name }}'))
+response_headers['{{ response_header.name }}']=self._deserialize('{{ response_header.serialization_type }}', response.headers.get('{{ response_header.name }}'))
     {% endfor %}
   {% endif %}
   {% if response.is_stream_response %}
 deserialized = response.stream_download(self._client._pipeline)
   {% elif response.has_body %}
-deserialized = self._deserialize('{{ response.schema.serialization_type }}', pipeline_response)
+deserialized = self._deserialize('{{ response.serialization_type }}', pipeline_response)
   {% endif %}
 {% endmacro %}
 {# write grouped parameters #}
@@ -130,15 +130,15 @@ if {{ header_parameter.full_serialized_name }} is not None:
 {% macro stream_body_params(operation) %}body_content_kwargs['stream_content'] = {{ operation.parameters.body[0].serialized_name }}{% endmacro %}
 {# helper for non-stream body params with schema #}
 {% macro non_stream_body_params(operation, send_xml, request_as_xml) %}
-{% set ser_ctxt = operation.parameters.body[0].schema.xml_serialization_ctxt() if send_xml else None %}
+{% set ser_ctxt = operation.parameters.body[0].xml_serialization_ctxt if send_xml else None %}
 {% if ser_ctxt %}
 serialization_ctxt = {'xml': {{ "{" }}{{ ser_ctxt }}{{ "}}" }}
 {% endif %}
 {% if operation.parameters.body[0].required %}
-body_content = self._serialize.body({{ operation.parameters.body[0].serialized_name }}, '{{ operation.parameters.body[0].schema.serialization_type }}'{{ request_as_xml }}{{ ", serialization_ctxt=serialization_ctxt" if ser_ctxt else "" }})
+body_content = self._serialize.body({{ operation.parameters.body[0].serialized_name }}, '{{ operation.parameters.body[0].serialization_type }}'{{ request_as_xml }}{{ ", serialization_ctxt=serialization_ctxt" if ser_ctxt else "" }})
 {% else %}
 if {{ operation.parameters.body[0].serialized_name }} is not None:
-    body_content = self._serialize.body({{ operation.parameters.body[0].serialized_name }}, '{{ operation.parameters.body[0].schema.serialization_type }}'{{ request_as_xml }}{{ ", serialization_ctxt=serialization_ctxt" if ser_ctxt else "" }})
+    body_content = self._serialize.body({{ operation.parameters.body[0].serialized_name }}, '{{ operation.parameters.body[0].serialization_type }}'{{ request_as_xml }}{{ ", serialization_ctxt=serialization_ctxt" if ser_ctxt else "" }})
 else:
     body_content = None
 {% endif %}
diff --git a/autorest/codegen/templates/paging_operation.py.jinja2 b/autorest/codegen/templates/paging_operation.py.jinja2
index 8514bfc2943..6cced477f83 100644
--- a/autorest/codegen/templates/paging_operation.py.jinja2
+++ b/autorest/codegen/templates/paging_operation.py.jinja2
@@ -5,9 +5,9 @@
 {% set item_paged = "AsyncItemPaged" if async_mode else "ItemPaged" %}
 {% macro return_docstring(async_mode) %}
 {% if operation.responses | selectattr('has_body') | first %}
-:return: An iterator like instance of either {{ operation.responses|selectattr('has_body')|map(attribute='schema')|map(attribute='docstring_text')|unique|join(' or ') }} or the result of cls(response)
+:return: An iterator like instance of either {{ operation.responses|selectattr('has_body')|map(attribute='docstring_text')|unique|join(' or ') }} or the result of cls(response)
 {# can't use item_paged variable, otherwise the call to get docstring from the metadata template will always return ItemPaged #}
-:rtype: ~azure.core.{{ "async_" if async_mode else "" }}paging.{{ "Async" if async_mode }}ItemPaged[{% for response in operation.responses %}{{response.schema.docstring_type if response.has_body else "None"}}{% if not loop.last -%} or {% endif %}{% endfor %}]
+:rtype: ~azure.core.{{ "async_" if async_mode else "" }}paging.{{ "Async" if async_mode }}ItemPaged[{% for response in operation.responses %}{{response.docstring_type if response.has_body else "None"}}{% if not loop.last -%} or {% endif %}{% endfor %}]
 {%- else -%}
 :return: None
 :rtype: None{%- endif -%}{%- endmacro -%}
@@ -27,7 +27,7 @@
 {%- for doc_string in param_documentation_string(parameter).replace('\n', '\n ').split('\n') %}
 {{ doc_string | wordwrap(width=95, break_long_words=False, wrapstring='\n ')}}
 {% endfor %}
-:type {{ parameter.serialized_name }}: {{ parameter.schema.docstring_type }}
+:type {{ parameter.serialized_name }}: {{ parameter.docstring_type }}
 {% endfor %}
 :keyword callable cls: A custom type or function that will be passed the direct response
 {{ return_docstring(async_mode) }}
diff --git a/autorest/codegen/templates/paging_operation_helper.jinja2 b/autorest/codegen/templates/paging_operation_helper.jinja2
index fe318dd8232..63a592262c0 100644
--- a/autorest/codegen/templates/paging_operation_helper.jinja2
+++ b/autorest/codegen/templates/paging_operation_helper.jinja2
@@ -13,7 +13,7 @@ cls = kwargs.pop('cls', None)  # type: ClsType[{{ op_tools.return_type_annotatio
 {% endif %}
 {% if operation.parameters.constant|selectattr("implementation", "equalto", "Method") %}
     {% for constant_parameter in operation.parameters.constant|selectattr("implementation", "equalto", "Method") %}
-    {{ constant_parameter.serialized_name }} = {{ constant_parameter.schema.get_declaration(constant_parameter.schema.value) }}
+    {{ constant_parameter.serialized_name }} = {{ constant_parameter.constant_declaration }}
     {% endfor %}
 {% endif %}
 
@@ -62,7 +62,7 @@ cls = kwargs.pop('cls', None)  # type: ClsType[{{ op_tools.return_type_annotatio
 
     {{ keywords.def }} extract_data(pipeline_response):
         {% set response = operation.responses[0] %}
-        deserialized = self._deserialize('{{ response.schema.serialization_type }}', pipeline_response)
+        deserialized = self._deserialize('{{ response.serialization_type }}', pipeline_response)
         list_of_elem = deserialized.{{ operation.item_name }}
         if cls:
             list_of_elem = cls(list_of_elem)
diff --git a/autorest/codegen/templates/service_client.py.jinja2 b/autorest/codegen/templates/service_client.py.jinja2
index 2b2e27ae3cf..a11734a9bf0 100644
--- a/autorest/codegen/templates/service_client.py.jinja2
+++ b/autorest/codegen/templates/service_client.py.jinja2
@@ -53,7 +53,7 @@ class {{ code_model.class_name }}({{ base_class }}):
     {% endfor %}
 {% for parameter in code_model.global_parameters.method %}
     :param {{ parameter.serialized_name }}: {{ parameter.description }}
-    :type {{ parameter.serialized_name }}: {{ parameter.schema.docstring_type }}
+    :type {{ parameter.serialized_name }}: {{ parameter.docstring_type }}
 {% endfor %}
     {% if not code_model.custom_base_url %}
     :param str base_url: Service URL
diff --git a/test/azure/Expected/AcceptanceTests/AzureBodyDuration/bodyduration/aio/operations/_duration_operations.py b/test/azure/Expected/AcceptanceTests/AzureBodyDuration/bodyduration/aio/operations/_duration_operations.py
index ac6d7e3e4a4..c34fbbb55d3 100644
--- a/test/azure/Expected/AcceptanceTests/AzureBodyDuration/bodyduration/aio/operations/_duration_operations.py
+++ b/test/azure/Expected/AcceptanceTests/AzureBodyDuration/bodyduration/aio/operations/_duration_operations.py
@@ -45,15 +45,15 @@ def __init__(self, client, config, serializer, deserializer) -> None:
     async def get_null(
         self,
         **kwargs
-    ) -> datetime.timedelta:
+    ) -> Optional[datetime.timedelta]:
         """Get null duration value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: timedelta, or the result of cls(response)
-        :rtype: ~datetime.timedelta
+        :return: timedelta or None, or the result of cls(response)
+        :rtype: ~datetime.timedelta or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[datetime.timedelta]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[datetime.timedelta]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/azure/Expected/AcceptanceTests/AzureBodyDuration/bodyduration/operations/_duration_operations.py b/test/azure/Expected/AcceptanceTests/AzureBodyDuration/bodyduration/operations/_duration_operations.py
index 06a0b8b5c55..ba3a5bd93c2 100644
--- a/test/azure/Expected/AcceptanceTests/AzureBodyDuration/bodyduration/operations/_duration_operations.py
+++ b/test/azure/Expected/AcceptanceTests/AzureBodyDuration/bodyduration/operations/_duration_operations.py
@@ -50,15 +50,15 @@ def get_null(
         self,
         **kwargs  # type: Any
     ):
-        # type: (...) -> datetime.timedelta
+        # type: (...) -> Optional[datetime.timedelta]
         """Get null duration value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: timedelta, or the result of cls(response)
-        :rtype: ~datetime.timedelta
+        :return: timedelta or None, or the result of cls(response)
+        :rtype: ~datetime.timedelta or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[datetime.timedelta]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[datetime.timedelta]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyBoolean/bodyboolean/aio/operations/_bool_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyBoolean/bodyboolean/aio/operations/_bool_operations.py
index 6d383bb6a00..e8787e26edb 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyBoolean/bodyboolean/aio/operations/_bool_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyBoolean/bodyboolean/aio/operations/_bool_operations.py
@@ -234,15 +234,15 @@ async def put_false(
     async def get_null(
         self,
         **kwargs
-    ) -> bool:
+    ) -> Optional[bool]:
         """Get null Boolean value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: bool, or the result of cls(response)
-        :rtype: bool
+        :return: bool or None, or the result of cls(response)
+        :rtype: bool or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[bool]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[bool]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyBoolean/bodyboolean/operations/_bool_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyBoolean/bodyboolean/operations/_bool_operations.py
index f24b5b0297b..841519490b1 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyBoolean/bodyboolean/operations/_bool_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyBoolean/bodyboolean/operations/_bool_operations.py
@@ -243,15 +243,15 @@ def get_null(
         self,
         **kwargs  # type: Any
     ):
-        # type: (...) -> bool
+        # type: (...) -> Optional[bool]
         """Get null Boolean value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: bool, or the result of cls(response)
-        :rtype: bool
+        :return: bool or None, or the result of cls(response)
+        :rtype: bool or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[bool]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[bool]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyDate/bodydate/aio/operations/_date_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyDate/bodydate/aio/operations/_date_operations.py
index bedd3a9e1fd..1b9ad1b206b 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyDate/bodydate/aio/operations/_date_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyDate/bodydate/aio/operations/_date_operations.py
@@ -45,15 +45,15 @@ def __init__(self, client, config, serializer, deserializer) -> None:
     async def get_null(
         self,
         **kwargs
-    ) -> datetime.date:
+    ) -> Optional[datetime.date]:
         """Get null date value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: date, or the result of cls(response)
-        :rtype: ~datetime.date
+        :return: date or None, or the result of cls(response)
+        :rtype: ~datetime.date or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[datetime.date]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[datetime.date]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyDate/bodydate/operations/_date_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyDate/bodydate/operations/_date_operations.py
index 1c7c6b6ab0b..16040be60be 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyDate/bodydate/operations/_date_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyDate/bodydate/operations/_date_operations.py
@@ -50,15 +50,15 @@ def get_null(
         self,
         **kwargs  # type: Any
     ):
-        # type: (...) -> datetime.date
+        # type: (...) -> Optional[datetime.date]
         """Get null date value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: date, or the result of cls(response)
-        :rtype: ~datetime.date
+        :return: date or None, or the result of cls(response)
+        :rtype: ~datetime.date or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[datetime.date]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[datetime.date]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyDateTime/bodydatetime/aio/operations/_datetime_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyDateTime/bodydatetime/aio/operations/_datetime_operations.py
index 809d5367cbb..485660616ac 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyDateTime/bodydatetime/aio/operations/_datetime_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyDateTime/bodydatetime/aio/operations/_datetime_operations.py
@@ -45,15 +45,15 @@ def __init__(self, client, config, serializer, deserializer) -> None:
     async def get_null(
         self,
         **kwargs
-    ) -> datetime.datetime:
+    ) -> Optional[datetime.datetime]:
         """Get null datetime value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: datetime, or the result of cls(response)
-        :rtype: ~datetime.datetime
+        :return: datetime or None, or the result of cls(response)
+        :rtype: ~datetime.datetime or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[datetime.datetime]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[datetime.datetime]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyDateTime/bodydatetime/operations/_datetime_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyDateTime/bodydatetime/operations/_datetime_operations.py
index 038d443bcab..e31a2dfc264 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyDateTime/bodydatetime/operations/_datetime_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyDateTime/bodydatetime/operations/_datetime_operations.py
@@ -50,15 +50,15 @@ def get_null(
         self,
         **kwargs  # type: Any
     ):
-        # type: (...) -> datetime.datetime
+        # type: (...) -> Optional[datetime.datetime]
         """Get null datetime value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: datetime, or the result of cls(response)
-        :rtype: ~datetime.datetime
+        :return: datetime or None, or the result of cls(response)
+        :rtype: ~datetime.datetime or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[datetime.datetime]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[datetime.datetime]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyDateTimeRfc1123/bodydatetimerfc1123/aio/operations/_datetimerfc1123_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyDateTimeRfc1123/bodydatetimerfc1123/aio/operations/_datetimerfc1123_operations.py
index 9cae5997fc5..7541fdcd221 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyDateTimeRfc1123/bodydatetimerfc1123/aio/operations/_datetimerfc1123_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyDateTimeRfc1123/bodydatetimerfc1123/aio/operations/_datetimerfc1123_operations.py
@@ -45,15 +45,15 @@ def __init__(self, client, config, serializer, deserializer) -> None:
     async def get_null(
         self,
         **kwargs
-    ) -> datetime.datetime:
+    ) -> Optional[datetime.datetime]:
         """Get null datetime value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: datetime, or the result of cls(response)
-        :rtype: ~datetime.datetime
+        :return: datetime or None, or the result of cls(response)
+        :rtype: ~datetime.datetime or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[datetime.datetime]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[datetime.datetime]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyDateTimeRfc1123/bodydatetimerfc1123/operations/_datetimerfc1123_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyDateTimeRfc1123/bodydatetimerfc1123/operations/_datetimerfc1123_operations.py
index 09357977cd3..29c511ad193 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyDateTimeRfc1123/bodydatetimerfc1123/operations/_datetimerfc1123_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyDateTimeRfc1123/bodydatetimerfc1123/operations/_datetimerfc1123_operations.py
@@ -50,15 +50,15 @@ def get_null(
         self,
         **kwargs  # type: Any
     ):
-        # type: (...) -> datetime.datetime
+        # type: (...) -> Optional[datetime.datetime]
         """Get null datetime value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: datetime, or the result of cls(response)
-        :rtype: ~datetime.datetime
+        :return: datetime or None, or the result of cls(response)
+        :rtype: ~datetime.datetime or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[datetime.datetime]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[datetime.datetime]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyDuration/bodyduration/aio/operations/_duration_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyDuration/bodyduration/aio/operations/_duration_operations.py
index ac6d7e3e4a4..c34fbbb55d3 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyDuration/bodyduration/aio/operations/_duration_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyDuration/bodyduration/aio/operations/_duration_operations.py
@@ -45,15 +45,15 @@ def __init__(self, client, config, serializer, deserializer) -> None:
     async def get_null(
         self,
         **kwargs
-    ) -> datetime.timedelta:
+    ) -> Optional[datetime.timedelta]:
         """Get null duration value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: timedelta, or the result of cls(response)
-        :rtype: ~datetime.timedelta
+        :return: timedelta or None, or the result of cls(response)
+        :rtype: ~datetime.timedelta or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[datetime.timedelta]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[datetime.timedelta]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyDuration/bodyduration/operations/_duration_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyDuration/bodyduration/operations/_duration_operations.py
index 06a0b8b5c55..ba3a5bd93c2 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyDuration/bodyduration/operations/_duration_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyDuration/bodyduration/operations/_duration_operations.py
@@ -50,15 +50,15 @@ def get_null(
         self,
         **kwargs  # type: Any
     ):
-        # type: (...) -> datetime.timedelta
+        # type: (...) -> Optional[datetime.timedelta]
         """Get null duration value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: timedelta, or the result of cls(response)
-        :rtype: ~datetime.timedelta
+        :return: timedelta or None, or the result of cls(response)
+        :rtype: ~datetime.timedelta or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[datetime.timedelta]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[datetime.timedelta]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyInteger/bodyinteger/aio/operations/_int_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyInteger/bodyinteger/aio/operations/_int_operations.py
index 029d1ff412a..65a59bc0c12 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyInteger/bodyinteger/aio/operations/_int_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyInteger/bodyinteger/aio/operations/_int_operations.py
@@ -45,15 +45,15 @@ def __init__(self, client, config, serializer, deserializer) -> None:
     async def get_null(
         self,
         **kwargs
-    ) -> int:
+    ) -> Optional[int]:
         """Get null Int value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: int, or the result of cls(response)
-        :rtype: int
+        :return: int or None, or the result of cls(response)
+        :rtype: int or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[int]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[int]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
@@ -668,15 +668,15 @@ async def get_invalid_unix_time(
     async def get_null_unix_time(
         self,
         **kwargs
-    ) -> datetime.datetime:
+    ) -> Optional[datetime.datetime]:
         """Get null Unix time value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: datetime, or the result of cls(response)
-        :rtype: ~datetime.datetime
+        :return: datetime or None, or the result of cls(response)
+        :rtype: ~datetime.datetime or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[datetime.datetime]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[datetime.datetime]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyInteger/bodyinteger/operations/_int_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyInteger/bodyinteger/operations/_int_operations.py
index a173b3e3a85..5e36a2036d2 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyInteger/bodyinteger/operations/_int_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyInteger/bodyinteger/operations/_int_operations.py
@@ -50,15 +50,15 @@ def get_null(
         self,
         **kwargs  # type: Any
     ):
-        # type: (...) -> int
+        # type: (...) -> Optional[int]
         """Get null Int value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: int, or the result of cls(response)
-        :rtype: int
+        :return: int or None, or the result of cls(response)
+        :rtype: int or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[int]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[int]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
@@ -686,15 +686,15 @@ def get_null_unix_time(
         self,
         **kwargs  # type: Any
     ):
-        # type: (...) -> datetime.datetime
+        # type: (...) -> Optional[datetime.datetime]
         """Get null Unix time value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: datetime, or the result of cls(response)
-        :rtype: ~datetime.datetime
+        :return: datetime or None, or the result of cls(response)
+        :rtype: ~datetime.datetime or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[datetime.datetime]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[datetime.datetime]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyNumber/bodynumber/aio/operations/_number_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyNumber/bodynumber/aio/operations/_number_operations.py
index 920d5975242..426e3c7d23e 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyNumber/bodynumber/aio/operations/_number_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyNumber/bodynumber/aio/operations/_number_operations.py
@@ -44,15 +44,15 @@ def __init__(self, client, config, serializer, deserializer) -> None:
     async def get_null(
         self,
         **kwargs
-    ) -> float:
+    ) -> Optional[float]:
         """Get null Number value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: float, or the result of cls(response)
-        :rtype: float
+        :return: float or None, or the result of cls(response)
+        :rtype: float or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[float]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[float]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyNumber/bodynumber/operations/_number_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyNumber/bodynumber/operations/_number_operations.py
index 66d36dea7d6..21f4b629777 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyNumber/bodynumber/operations/_number_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyNumber/bodynumber/operations/_number_operations.py
@@ -49,15 +49,15 @@ def get_null(
         self,
         **kwargs  # type: Any
     ):
-        # type: (...) -> float
+        # type: (...) -> Optional[float]
         """Get null Number value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: float, or the result of cls(response)
-        :rtype: float
+        :return: float or None, or the result of cls(response)
+        :rtype: float or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[float]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[float]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyString/bodystring/aio/operations/_string_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyString/bodystring/aio/operations/_string_operations.py
index 95b0b5531d6..f79b8888072 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyString/bodystring/aio/operations/_string_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyString/bodystring/aio/operations/_string_operations.py
@@ -44,15 +44,15 @@ def __init__(self, client, config, serializer, deserializer) -> None:
     async def get_null(
         self,
         **kwargs
-    ) -> str:
+    ) -> Optional[str]:
         """Get null string value value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: str, or the result of cls(response)
-        :rtype: str
+        :return: str or None, or the result of cls(response)
+        :rtype: str or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[str]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[str]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
@@ -622,15 +622,15 @@ async def put_base64_url_encoded(
     async def get_null_base64_url_encoded(
         self,
         **kwargs
-    ) -> bytes:
+    ) -> Optional[bytes]:
         """Get null value that is expected to be base64url encoded.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: bytes, or the result of cls(response)
-        :rtype: bytes
+        :return: bytes or None, or the result of cls(response)
+        :rtype: bytes or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[bytes]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[bytes]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
diff --git a/test/vanilla/Expected/AcceptanceTests/BodyString/bodystring/operations/_string_operations.py b/test/vanilla/Expected/AcceptanceTests/BodyString/bodystring/operations/_string_operations.py
index d6036a31837..236d2c69754 100644
--- a/test/vanilla/Expected/AcceptanceTests/BodyString/bodystring/operations/_string_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/BodyString/bodystring/operations/_string_operations.py
@@ -49,15 +49,15 @@ def get_null(
         self,
         **kwargs  # type: Any
     ):
-        # type: (...) -> str
+        # type: (...) -> Optional[str]
         """Get null string value value.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: str, or the result of cls(response)
-        :rtype: str
+        :return: str or None, or the result of cls(response)
+        :rtype: str or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[str]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[str]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }
@@ -639,15 +639,15 @@ def get_null_base64_url_encoded(
         self,
         **kwargs  # type: Any
     ):
-        # type: (...) -> bytes
+        # type: (...) -> Optional[bytes]
         """Get null value that is expected to be base64url encoded.
 
         :keyword callable cls: A custom type or function that will be passed the direct response
-        :return: bytes, or the result of cls(response)
-        :rtype: bytes
+        :return: bytes or None, or the result of cls(response)
+        :rtype: bytes or None
         :raises: ~azure.core.exceptions.HttpResponseError
         """
-        cls = kwargs.pop('cls', None)  # type: ClsType[bytes]
+        cls = kwargs.pop('cls', None)  # type: ClsType[Optional[bytes]]
         error_map = {
             401: ClientAuthenticationError, 404: ResourceNotFoundError, 409: ResourceExistsError
         }