diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenModel.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenModel.java
index 760033ec35de..f9d25b47d251 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenModel.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenModel.java
@@ -595,4 +595,8 @@ public void removeSelfReferenceImport() {
             }
         }
     }
+
+    public boolean isComposed() {
+        return !allOf.isEmpty() || !oneOf.isEmpty() || !anyOf.isEmpty();
+    }
 }
diff --git a/modules/openapi-generator/src/main/resources/python/api_client.mustache b/modules/openapi-generator/src/main/resources/python/api_client.mustache
index 768b8d973f8f..7af5bc0ce6f3 100644
--- a/modules/openapi-generator/src/main/resources/python/api_client.mustache
+++ b/modules/openapi-generator/src/main/resources/python/api_client.mustache
@@ -72,6 +72,7 @@ class ApiClient(object):
         self.cookie = cookie
         # Set default User-Agent.
         self.user_agent = '{{#httpUserAgent}}{{{.}}}{{/httpUserAgent}}{{^httpUserAgent}}OpenAPI-Generator/{{{packageVersion}}}/python{{/httpUserAgent}}'
+        self.__deserializer_track = []
 
     def __del__(self):
         if self._pool:
@@ -268,6 +269,7 @@ class ApiClient(object):
         """
         if data is None:
             return None
+        self.__deserializer_track.append(klass)
 
         if type(klass) == str:
             if klass.startswith('list['):
@@ -640,6 +642,60 @@ class ApiClient(object):
 
         instance = klass(**kwargs)
 
+        if hasattr(instance, 'composed_hierarchy'):
+            hierarchy = instance.composed_hierarchy
+            if sum([1 if v else 0 for v in hierarchy.values()]) > 1:
+                # ignore implicit AllOf
+                return instance
+
+            def error_msg(composed):
+                return "Failed to parse `{0}` as {1} ({2} {3})" \
+                    .format(data, klass,
+                            composed,
+                            ' '.join(hierarchy[composed]))
+
+            if hierarchy['allOf']:
+                matches = []
+                for sub_klass in hierarchy['allOf']:
+                    try:
+                        if sub_klass in self.__deserializer_track:
+                            # seen it before, break the recursion
+                            matches.append(None)
+                        else:
+                            matches.append(self.__deserialize(data, sub_klass))
+                    except:  # noqa: E722
+                        pass
+                if len(matches) == len(hierarchy['allOf']):
+                    self.__deserializer_track = []
+                    return instance
+
+                # not all matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('allOf'))
+
+            if hierarchy['anyOf']:
+                for sub_klass in hierarchy['anyOf']:
+                    try:
+                        # if at least one of the sub-class matches
+                        # terminate with an instance of this class
+                        return self.__deserialize(data, sub_klass)
+                    except:  # noqa: E722
+                        pass
+                # none matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('anyOf'))
+
+            if hierarchy['oneOf']:
+                matches = []
+                for sub_klass in hierarchy['oneOf']:
+                    try:
+                        matches.append(self.__deserialize(data, sub_klass))
+                    except:  # noqa: E722
+                        pass
+                if len(matches) == 1:
+                    return matches[0]
+
+                # none matched, or more than one matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('oneOf'))
+
         if hasattr(instance, 'get_real_child_model'):
             klass_name = instance.get_real_child_model(data)
             if klass_name:
diff --git a/modules/openapi-generator/src/main/resources/python/model.mustache b/modules/openapi-generator/src/main/resources/python/model.mustache
index 16c8dadbf620..f7d9cda91e5c 100644
--- a/modules/openapi-generator/src/main/resources/python/model.mustache
+++ b/modules/openapi-generator/src/main/resources/python/model.mustache
@@ -49,6 +49,16 @@ class {{classname}}(object):
         {{#children}}'{{^vendorExtensions.x-discriminator-value}}{{name}}{{/vendorExtensions.x-discriminator-value}}{{#vendorExtensions.x-discriminator-value}}{{{vendorExtensions.x-discriminator-value}}}{{/vendorExtensions.x-discriminator-value}}': '{{{classname}}}'{{^-last}},
         {{/-last}}{{/children}}
     }
+{{/discriminator}}
+{{^discriminator}}
+{{#isComposed}}
+
+    composed_hierarchy = {
+        'anyOf': [{{#anyOf}}"{{.}}"{{^-last}}, {{/-last}}{{/anyOf}}],
+        'allOf': [{{#allOf}}"{{.}}"{{^-last}}, {{/-last}}{{/allOf}}],
+        'oneOf': [{{#oneOf}}"{{.}}"{{^-last}}, {{/-last}}{{/oneOf}}],
+    }
+{{/isComposed}}
 {{/discriminator}}
 
     def __init__(self{{#vars}}, {{name}}={{#defaultValue}}{{{defaultValue}}}{{/defaultValue}}{{^defaultValue}}None{{/defaultValue}}{{/vars}}):  # noqa: E501
diff --git a/samples/client/petstore-security-test/python/petstore_api/api_client.py b/samples/client/petstore-security-test/python/petstore_api/api_client.py
new file mode 100644
index 000000000000..3a356c64a950
--- /dev/null
+++ b/samples/client/petstore-security-test/python/petstore_api/api_client.py
@@ -0,0 +1,697 @@
+# coding: utf-8
+"""
+    OpenAPI Petstore */ ' \" =end -- \\r\\n \\n \\r
+
+    This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\  */ ' \" =end --         # noqa: E501
+
+    OpenAPI spec version: 1.0.0 */ ' \" =end -- \\r\\n \\n \\r
+    Contact: something@something.abc */ ' \" =end -- \\r\\n \\n \\r
+    Generated by: https://openapi-generator.tech
+"""
+
+from __future__ import absolute_import
+
+import datetime
+import json
+import mimetypes
+from multiprocessing.pool import ThreadPool
+import os
+import re
+import tempfile
+
+# python 2 and python 3 compatibility library
+import six
+from six.moves.urllib.parse import quote
+
+from petstore_api.configuration import Configuration
+import petstore_api.models
+from petstore_api import rest
+
+
+class ApiClient(object):
+    """Generic API client for OpenAPI client library builds.
+
+    OpenAPI generic API client. This client handles the client-
+    server communication, and is invariant across implementations. Specifics of
+    the methods and models for each application are generated from the OpenAPI
+    templates.
+
+    NOTE: This class is auto generated by OpenAPI Generator.
+    Ref: https://openapi-generator.tech
+    Do not edit the class manually.
+
+    :param configuration: .Configuration object for this client
+    :param header_name: a header to pass when making calls to the API.
+    :param header_value: a header value to pass when making calls to
+        the API.
+    :param cookie: a cookie to include in the header when making calls
+        to the API
+    :param pool_threads: The number of threads to use for async requests
+        to the API. More threads means more concurrent API requests.
+    """
+
+    PRIMITIVE_TYPES = (float, bool, bytes, six.text_type) + six.integer_types
+    NATIVE_TYPES_MAPPING = {
+        'int': int,
+        'long': int if six.PY3 else long,  # noqa: F821
+        'float': float,
+        'str': str,
+        'bool': bool,
+        'date': datetime.date,
+        'datetime': datetime.datetime,
+        'object': object,
+    }
+    _pool = None
+
+    def __init__(self, configuration=None, header_name=None, header_value=None,
+                 cookie=None, pool_threads=1):
+        if configuration is None:
+            configuration = Configuration()
+        self.configuration = configuration
+        self.pool_threads = pool_threads
+
+        self.rest_client = rest.RESTClientObject(configuration)
+        self.default_headers = {}
+        if header_name is not None:
+            self.default_headers[header_name] = header_value
+        self.cookie = cookie
+        # Set default User-Agent.
+        self.user_agent = 'OpenAPI-Generator/1.0.0/python'
+        self.__deserializer_track = []
+
+    def __del__(self):
+        if self._pool:
+            self._pool.close()
+            self._pool.join()
+            self._pool = None
+
+    @property
+    def pool(self):
+        """Create thread pool on first request
+         avoids instantiating unused threadpool for blocking clients.
+        """
+        if self._pool is None:
+            self._pool = ThreadPool(self.pool_threads)
+        return self._pool
+
+    @property
+    def user_agent(self):
+        """User agent for this API client"""
+        return self.default_headers['User-Agent']
+
+    @user_agent.setter
+    def user_agent(self, value):
+        self.default_headers['User-Agent'] = value
+
+    def set_default_header(self, header_name, header_value):
+        self.default_headers[header_name] = header_value
+
+    def __call_api(
+            self, resource_path, method, path_params=None,
+            query_params=None, header_params=None, body=None, post_params=None,
+            files=None, response_type=None, auth_settings=None,
+            _return_http_data_only=None, collection_formats=None,
+            _preload_content=True, _request_timeout=None, _host=None):
+
+        config = self.configuration
+
+        # header parameters
+        header_params = header_params or {}
+        header_params.update(self.default_headers)
+        if self.cookie:
+            header_params['Cookie'] = self.cookie
+        if header_params:
+            header_params = self.sanitize_for_serialization(header_params)
+            header_params = dict(self.parameters_to_tuples(header_params,
+                                                           collection_formats))
+
+        # path parameters
+        if path_params:
+            path_params = self.sanitize_for_serialization(path_params)
+            path_params = self.parameters_to_tuples(path_params,
+                                                    collection_formats)
+            for k, v in path_params:
+                # specified safe chars, encode everything
+                resource_path = resource_path.replace(
+                    '{%s}' % k,
+                    quote(str(v), safe=config.safe_chars_for_path_param)
+                )
+
+        # query parameters
+        if query_params:
+            query_params = self.sanitize_for_serialization(query_params)
+            query_params = self.parameters_to_tuples(query_params,
+                                                     collection_formats)
+
+        # post parameters
+        if post_params or files:
+            post_params = self.prepare_post_parameters(post_params, files)
+            post_params = self.sanitize_for_serialization(post_params)
+            post_params = self.parameters_to_tuples(post_params,
+                                                    collection_formats)
+
+        # auth setting
+        self.update_params_for_auth(header_params, query_params, auth_settings)
+
+        # body
+        if body:
+            body = self.sanitize_for_serialization(body)
+
+        # request url
+        if _host is None:
+            url = self.configuration.host + resource_path
+        else:
+            # use server/host defined in path or operation instead
+            url = _host + resource_path
+
+        # perform request and return response
+        response_data = self.request(
+            method, url, query_params=query_params, headers=header_params,
+            post_params=post_params, body=body,
+            _preload_content=_preload_content,
+            _request_timeout=_request_timeout)
+
+        self.last_response = response_data
+
+        return_data = response_data
+        if _preload_content:
+            # deserialize response data
+            if response_type:
+                return_data = self.deserialize(response_data, response_type)
+            else:
+                return_data = None
+
+        if _return_http_data_only:
+            return (return_data)
+        else:
+            return (return_data, response_data.status,
+                    response_data.getheaders())
+
+    def sanitize_for_serialization(self, obj):
+        """Builds a JSON POST object.
+
+        If obj is None, return None.
+        If obj is str, int, long, float, bool, return directly.
+        If obj is datetime.datetime, datetime.date
+            convert to string in iso8601 format.
+        If obj is list, sanitize each element in the list.
+        If obj is dict, return the dict.
+        If obj is OpenAPI model, return the properties dict.
+
+        :param obj: The data to serialize.
+        :return: The serialized form of data.
+        """
+        if obj is None:
+            return None
+        elif isinstance(obj, self.PRIMITIVE_TYPES):
+            return obj
+        elif isinstance(obj, list):
+            return [self.sanitize_for_serialization(sub_obj)
+                    for sub_obj in obj]
+        elif isinstance(obj, tuple):
+            return tuple(self.sanitize_for_serialization(sub_obj)
+                         for sub_obj in obj)
+        elif isinstance(obj, (datetime.datetime, datetime.date)):
+            return obj.isoformat()
+
+        if isinstance(obj, dict):
+            obj_dict = obj
+        else:
+            # Convert model obj to dict except
+            # attributes `openapi_types`, `attribute_map`
+            # and attributes which value is not None.
+            # Convert attribute name to json key in
+            # model definition for request.
+            obj_dict = {obj.attribute_map[attr]: getattr(obj, attr)
+                        for attr, _ in six.iteritems(obj.openapi_types)
+                        if getattr(obj, attr) is not None}
+
+        return {key: self.sanitize_for_serialization(val)
+                for key, val in six.iteritems(obj_dict)}
+
+    def deserialize(self, response, response_type):
+        """Deserializes response into an object.
+
+        :param response: RESTResponse object to be deserialized.
+        :param response_type: class literal for
+            deserialized object, or string of class name.
+
+        :return: deserialized object.
+        """
+        # handle file downloading
+        # save response body into a tmp file and return the instance
+        if response_type == "file":
+            return self.__deserialize_file(response)
+
+        # fetch data from response object
+        try:
+            data = json.loads(response.data)
+        except ValueError:
+            data = response.data
+
+        return self.__deserialize(data, response_type)
+
+    def __deserialize(self, data, klass):
+        """Deserializes dict, list, str into an object.
+
+        :param data: dict, list or str.
+        :param klass: class literal, or string of class name.
+
+        :return: object.
+        """
+        if data is None:
+            return None
+        self.__deserializer_track.append(klass)
+
+        if type(klass) == str:
+            if klass.startswith('list['):
+                sub_kls = re.match(r'list\[(.*)\]', klass).group(1)
+                return [self.__deserialize(sub_data, sub_kls)
+                        for sub_data in data]
+
+            if klass.startswith('dict('):
+                sub_kls = re.match(r'dict\(([^,]*), (.*)\)', klass).group(2)
+                return {k: self.__deserialize(v, sub_kls)
+                        for k, v in six.iteritems(data)}
+
+            # convert str to class
+            if klass in self.NATIVE_TYPES_MAPPING:
+                klass = self.NATIVE_TYPES_MAPPING[klass]
+            else:
+                klass = getattr(petstore_api.models, klass)
+
+        if klass in self.PRIMITIVE_TYPES:
+            return self.__deserialize_primitive(data, klass)
+        elif klass == object:
+            return self.__deserialize_object(data)
+        elif klass == datetime.date:
+            return self.__deserialize_date(data)
+        elif klass == datetime.datetime:
+            return self.__deserialize_datatime(data)
+        else:
+            return self.__deserialize_model(data, klass)
+
+    def call_api(self, resource_path, method,
+                 path_params=None, query_params=None, header_params=None,
+                 body=None, post_params=None, files=None,
+                 response_type=None, auth_settings=None, async_req=None,
+                 _return_http_data_only=None, collection_formats=None,
+                 _preload_content=True, _request_timeout=None, _host=None):
+        """Makes the HTTP request (synchronous) and returns deserialized data.
+
+        To make an async_req request, set the async_req parameter.
+
+        :param resource_path: Path to method endpoint.
+        :param method: Method to call.
+        :param path_params: Path parameters in the url.
+        :param query_params: Query parameters in the url.
+        :param header_params: Header parameters to be
+            placed in the request header.
+        :param body: Request body.
+        :param post_params dict: Request post form parameters,
+            for `application/x-www-form-urlencoded`, `multipart/form-data`.
+        :param auth_settings list: Auth Settings names for the request.
+        :param response: Response data type.
+        :param files dict: key -> filename, value -> filepath,
+            for `multipart/form-data`.
+        :param async_req bool: execute request asynchronously
+        :param _return_http_data_only: response data without head status code
+                                       and headers
+        :param collection_formats: dict of collection formats for path, query,
+            header, and post parameters.
+        :param _preload_content: if False, the urllib3.HTTPResponse object will
+                                 be returned without reading/decoding response
+                                 data. Default is True.
+        :param _request_timeout: timeout setting for this request. If one
+                                 number provided, it will be total request
+                                 timeout. It can also be a pair (tuple) of
+                                 (connection, read) timeouts.
+        :return:
+            If async_req parameter is True,
+            the request will be called asynchronously.
+            The method will return the request thread.
+            If parameter async_req is False or missing,
+            then the method will return the response directly.
+        """
+        if not async_req:
+            return self.__call_api(resource_path, method,
+                                   path_params, query_params, header_params,
+                                   body, post_params, files,
+                                   response_type, auth_settings,
+                                   _return_http_data_only, collection_formats,
+                                   _preload_content, _request_timeout, _host)
+        else:
+            thread = self.pool.apply_async(self.__call_api, (resource_path,
+                                           method, path_params, query_params,
+                                           header_params, body,
+                                           post_params, files,
+                                           response_type, auth_settings,
+                                           _return_http_data_only,
+                                           collection_formats,
+                                           _preload_content,
+                                           _request_timeout,
+                                           _host))
+        return thread
+
+    def request(self, method, url, query_params=None, headers=None,
+                post_params=None, body=None, _preload_content=True,
+                _request_timeout=None):
+        """Makes the HTTP request using RESTClient."""
+        if method == "GET":
+            return self.rest_client.GET(url,
+                                        query_params=query_params,
+                                        _preload_content=_preload_content,
+                                        _request_timeout=_request_timeout,
+                                        headers=headers)
+        elif method == "HEAD":
+            return self.rest_client.HEAD(url,
+                                         query_params=query_params,
+                                         _preload_content=_preload_content,
+                                         _request_timeout=_request_timeout,
+                                         headers=headers)
+        elif method == "OPTIONS":
+            return self.rest_client.OPTIONS(url,
+                                            query_params=query_params,
+                                            headers=headers,
+                                            post_params=post_params,
+                                            _preload_content=_preload_content,
+                                            _request_timeout=_request_timeout,
+                                            body=body)
+        elif method == "POST":
+            return self.rest_client.POST(url,
+                                         query_params=query_params,
+                                         headers=headers,
+                                         post_params=post_params,
+                                         _preload_content=_preload_content,
+                                         _request_timeout=_request_timeout,
+                                         body=body)
+        elif method == "PUT":
+            return self.rest_client.PUT(url,
+                                        query_params=query_params,
+                                        headers=headers,
+                                        post_params=post_params,
+                                        _preload_content=_preload_content,
+                                        _request_timeout=_request_timeout,
+                                        body=body)
+        elif method == "PATCH":
+            return self.rest_client.PATCH(url,
+                                          query_params=query_params,
+                                          headers=headers,
+                                          post_params=post_params,
+                                          _preload_content=_preload_content,
+                                          _request_timeout=_request_timeout,
+                                          body=body)
+        elif method == "DELETE":
+            return self.rest_client.DELETE(url,
+                                           query_params=query_params,
+                                           headers=headers,
+                                           _preload_content=_preload_content,
+                                           _request_timeout=_request_timeout,
+                                           body=body)
+        else:
+            raise ValueError(
+                "http method must be `GET`, `HEAD`, `OPTIONS`,"
+                " `POST`, `PATCH`, `PUT` or `DELETE`."
+            )
+
+    def parameters_to_tuples(self, params, collection_formats):
+        """Get parameters as list of tuples, formatting collections.
+
+        :param params: Parameters as dict or list of two-tuples
+        :param dict collection_formats: Parameter collection formats
+        :return: Parameters as list of tuples, collections formatted
+        """
+        new_params = []
+        if collection_formats is None:
+            collection_formats = {}
+        for k, v in six.iteritems(params) if isinstance(params, dict) else params:  # noqa: E501
+            if k in collection_formats:
+                collection_format = collection_formats[k]
+                if collection_format == 'multi':
+                    new_params.extend((k, value) for value in v)
+                else:
+                    if collection_format == 'ssv':
+                        delimiter = ' '
+                    elif collection_format == 'tsv':
+                        delimiter = '\t'
+                    elif collection_format == 'pipes':
+                        delimiter = '|'
+                    else:  # csv is the default
+                        delimiter = ','
+                    new_params.append(
+                        (k, delimiter.join(str(value) for value in v)))
+            else:
+                new_params.append((k, v))
+        return new_params
+
+    def prepare_post_parameters(self, post_params=None, files=None):
+        """Builds form parameters.
+
+        :param post_params: Normal form parameters.
+        :param files: File parameters.
+        :return: Form parameters with files.
+        """
+        params = []
+
+        if post_params:
+            params = post_params
+
+        if files:
+            for k, v in six.iteritems(files):
+                if not v:
+                    continue
+                file_names = v if type(v) is list else [v]
+                for n in file_names:
+                    with open(n, 'rb') as f:
+                        filename = os.path.basename(f.name)
+                        filedata = f.read()
+                        mimetype = (mimetypes.guess_type(filename)[0] or
+                                    'application/octet-stream')
+                        params.append(
+                            tuple([k, tuple([filename, filedata, mimetype])]))
+
+        return params
+
+    def select_header_accept(self, accepts):
+        """Returns `Accept` based on an array of accepts provided.
+
+        :param accepts: List of headers.
+        :return: Accept (e.g. application/json).
+        """
+        if not accepts:
+            return
+
+        accepts = [x.lower() for x in accepts]
+
+        if 'application/json' in accepts:
+            return 'application/json'
+        else:
+            return ', '.join(accepts)
+
+    def select_header_content_type(self, content_types):
+        """Returns `Content-Type` based on an array of content_types provided.
+
+        :param content_types: List of content-types.
+        :return: Content-Type (e.g. application/json).
+        """
+        if not content_types:
+            return 'application/json'
+
+        content_types = [x.lower() for x in content_types]
+
+        if 'application/json' in content_types or '*/*' in content_types:
+            return 'application/json'
+        else:
+            return content_types[0]
+
+    def update_params_for_auth(self, headers, querys, auth_settings):
+        """Updates header and query params based on authentication setting.
+
+        :param headers: Header parameters dict to be updated.
+        :param querys: Query parameters tuple list to be updated.
+        :param auth_settings: Authentication setting identifiers list.
+        """
+        if not auth_settings:
+            return
+
+        for auth in auth_settings:
+            auth_setting = self.configuration.auth_settings().get(auth)
+            if auth_setting:
+                if not auth_setting['value']:
+                    continue
+                elif auth_setting['in'] == 'header':
+                    headers[auth_setting['key']] = auth_setting['value']
+                elif auth_setting['in'] == 'query':
+                    querys.append((auth_setting['key'], auth_setting['value']))
+                else:
+                    raise ValueError(
+                        'Authentication token must be in `query` or `header`'
+                    )
+
+    def __deserialize_file(self, response):
+        """Deserializes body to file
+
+        Saves response body into a file in a temporary folder,
+        using the filename from the `Content-Disposition` header if provided.
+
+        :param response:  RESTResponse.
+        :return: file path.
+        """
+        fd, path = tempfile.mkstemp(dir=self.configuration.temp_folder_path)
+        os.close(fd)
+        os.remove(path)
+
+        content_disposition = response.getheader("Content-Disposition")
+        if content_disposition:
+            filename = re.search(r'filename=[\'"]?([^\'"\s]+)[\'"]?',
+                                 content_disposition).group(1)
+            path = os.path.join(os.path.dirname(path), filename)
+
+        with open(path, "wb") as f:
+            f.write(response.data)
+
+        return path
+
+    def __deserialize_primitive(self, data, klass):
+        """Deserializes string to primitive type.
+
+        :param data: str.
+        :param klass: class literal.
+
+        :return: int, long, float, str, bool.
+        """
+        try:
+            return klass(data)
+        except UnicodeEncodeError:
+            return six.text_type(data)
+        except TypeError:
+            return data
+
+    def __deserialize_object(self, value):
+        """Return an original value.
+
+        :return: object.
+        """
+        return value
+
+    def __deserialize_date(self, string):
+        """Deserializes string to date.
+
+        :param string: str.
+        :return: date.
+        """
+        try:
+            from dateutil.parser import parse
+            return parse(string).date()
+        except ImportError:
+            return string
+        except ValueError:
+            raise rest.ApiException(
+                status=0,
+                reason="Failed to parse `{0}` as date object".format(string)
+            )
+
+    def __deserialize_datatime(self, string):
+        """Deserializes string to datetime.
+
+        The string should be in iso8601 datetime format.
+
+        :param string: str.
+        :return: datetime.
+        """
+        try:
+            from dateutil.parser import parse
+            return parse(string)
+        except ImportError:
+            return string
+        except ValueError:
+            raise rest.ApiException(
+                status=0,
+                reason=(
+                    "Failed to parse `{0}` as datetime object"
+                    .format(string)
+                )
+            )
+
+    def __deserialize_model(self, data, klass):
+        """Deserializes list or dict to model.
+
+        :param data: dict, list.
+        :param klass: class literal.
+        :return: model object.
+        """
+
+        if not klass.openapi_types and not hasattr(klass,
+                                                   'get_real_child_model'):
+            return data
+
+        kwargs = {}
+        if klass.openapi_types is not None:
+            for attr, attr_type in six.iteritems(klass.openapi_types):
+                if (data is not None and
+                        klass.attribute_map[attr] in data and
+                        isinstance(data, (list, dict))):
+                    value = data[klass.attribute_map[attr]]
+                    kwargs[attr] = self.__deserialize(value, attr_type)
+
+        instance = klass(**kwargs)
+
+        if hasattr(instance, 'composed_hierarchy'):
+            hierarchy = instance.composed_hierarchy
+            if sum([1 if v else 0 for v in hierarchy.values()]) > 1:
+                # ignore implicit AllOf
+                return instance
+
+            def error_msg(composed):
+                return "Failed to parse `{0}` as {1} ({2} {3})" \
+                    .format(data, klass,
+                            composed,
+                            ' '.join(hierarchy[composed]))
+
+            if hierarchy['allOf']:
+                matches = []
+                for sub_klass in hierarchy['allOf']:
+                    try:
+                        if sub_klass in self.__deserializer_track:
+                            # seen it before, break the recursion
+                            matches.append(None)
+                        else:
+                            matches.append(self.__deserialize(data, sub_klass))
+                    except:  # noqa: E722
+                        pass
+                if len(matches) == len(hierarchy['allOf']):
+                    self.__deserializer_track = []
+                    return instance
+
+                # not all matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('allOf'))
+
+            if hierarchy['anyOf']:
+                for sub_klass in hierarchy['anyOf']:
+                    try:
+                        # if at least one of the sub-class matches
+                        # terminate with an instance of this class
+                        return self.__deserialize(data, sub_klass)
+                    except:  # noqa: E722
+                        pass
+                # none matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('anyOf'))
+
+            if hierarchy['oneOf']:
+                matches = []
+                for sub_klass in hierarchy['oneOf']:
+                    try:
+                        matches.append(self.__deserialize(data, sub_klass))
+                    except:  # noqa: E722
+                        pass
+                if len(matches) == 1:
+                    return matches[0]
+
+                # none matched, or more than one matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('oneOf'))
+
+        if hasattr(instance, 'get_real_child_model'):
+            klass_name = instance.get_real_child_model(data)
+            if klass_name:
+                instance = self.__deserialize(data, klass_name)
+        return instance
diff --git a/samples/client/petstore/python-asyncio/petstore_api/api_client.py b/samples/client/petstore/python-asyncio/petstore_api/api_client.py
index c6fc3a0609cd..515bed38fdae 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/api_client.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/api_client.py
@@ -77,6 +77,7 @@ def __init__(self, configuration=None, header_name=None, header_value=None,
         self.cookie = cookie
         # Set default User-Agent.
         self.user_agent = 'OpenAPI-Generator/1.0.0/python'
+        self.__deserializer_track = []
 
     def __del__(self):
         if self._pool:
@@ -261,6 +262,7 @@ def __deserialize(self, data, klass):
         """
         if data is None:
             return None
+        self.__deserializer_track.append(klass)
 
         if type(klass) == str:
             if klass.startswith('list['):
@@ -633,6 +635,60 @@ def __deserialize_model(self, data, klass):
 
         instance = klass(**kwargs)
 
+        if hasattr(instance, 'composed_hierarchy'):
+            hierarchy = instance.composed_hierarchy
+            if sum([1 if v else 0 for v in hierarchy.values()]) > 1:
+                # ignore implicit AllOf
+                return instance
+
+            def error_msg(composed):
+                return "Failed to parse `{0}` as {1} ({2} {3})" \
+                    .format(data, klass,
+                            composed,
+                            ' '.join(hierarchy[composed]))
+
+            if hierarchy['allOf']:
+                matches = []
+                for sub_klass in hierarchy['allOf']:
+                    try:
+                        if sub_klass in self.__deserializer_track:
+                            # seen it before, break the recursion
+                            matches.append(None)
+                        else:
+                            matches.append(self.__deserialize(data, sub_klass))
+                    except:  # noqa: E722
+                        pass
+                if len(matches) == len(hierarchy['allOf']):
+                    self.__deserializer_track = []
+                    return instance
+
+                # not all matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('allOf'))
+
+            if hierarchy['anyOf']:
+                for sub_klass in hierarchy['anyOf']:
+                    try:
+                        # if at least one of the sub-class matches
+                        # terminate with an instance of this class
+                        return self.__deserialize(data, sub_klass)
+                    except:  # noqa: E722
+                        pass
+                # none matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('anyOf'))
+
+            if hierarchy['oneOf']:
+                matches = []
+                for sub_klass in hierarchy['oneOf']:
+                    try:
+                        matches.append(self.__deserialize(data, sub_klass))
+                    except:  # noqa: E722
+                        pass
+                if len(matches) == 1:
+                    return matches[0]
+
+                # none matched, or more than one matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('oneOf'))
+
         if hasattr(instance, 'get_real_child_model'):
             klass_name = instance.get_real_child_model(data)
             if klass_name:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/cat.py b/samples/client/petstore/python-asyncio/petstore_api/models/cat.py
index 216e5123538c..009c310a694a 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/cat.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/cat.py
@@ -38,6 +38,12 @@ class Cat(object):
         'declawed': 'declawed'
     }
 
+    composed_hierarchy = {
+        'anyOf': [],
+        'allOf': ["Animal", "CatAllOf"],
+        'oneOf': [],
+    }
+
     def __init__(self, declawed=None):  # noqa: E501
         """Cat - a model defined in OpenAPI"""  # noqa: E501
 
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/dog.py b/samples/client/petstore/python-asyncio/petstore_api/models/dog.py
index c325cb252c32..fb3dc6740796 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/dog.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/dog.py
@@ -38,6 +38,12 @@ class Dog(object):
         'breed': 'breed'
     }
 
+    composed_hierarchy = {
+        'anyOf': [],
+        'allOf': ["Animal", "DogAllOf"],
+        'oneOf': [],
+    }
+
     def __init__(self, breed=None):  # noqa: E501
         """Dog - a model defined in OpenAPI"""  # noqa: E501
 
diff --git a/samples/client/petstore/python-tornado/petstore_api/api_client.py b/samples/client/petstore/python-tornado/petstore_api/api_client.py
index 59c17a32f28b..8944af1960a4 100644
--- a/samples/client/petstore/python-tornado/petstore_api/api_client.py
+++ b/samples/client/petstore/python-tornado/petstore_api/api_client.py
@@ -78,6 +78,7 @@ def __init__(self, configuration=None, header_name=None, header_value=None,
         self.cookie = cookie
         # Set default User-Agent.
         self.user_agent = 'OpenAPI-Generator/1.0.0/python'
+        self.__deserializer_track = []
 
     def __del__(self):
         if self._pool:
@@ -263,6 +264,7 @@ def __deserialize(self, data, klass):
         """
         if data is None:
             return None
+        self.__deserializer_track.append(klass)
 
         if type(klass) == str:
             if klass.startswith('list['):
@@ -635,6 +637,60 @@ def __deserialize_model(self, data, klass):
 
         instance = klass(**kwargs)
 
+        if hasattr(instance, 'composed_hierarchy'):
+            hierarchy = instance.composed_hierarchy
+            if sum([1 if v else 0 for v in hierarchy.values()]) > 1:
+                # ignore implicit AllOf
+                return instance
+
+            def error_msg(composed):
+                return "Failed to parse `{0}` as {1} ({2} {3})" \
+                    .format(data, klass,
+                            composed,
+                            ' '.join(hierarchy[composed]))
+
+            if hierarchy['allOf']:
+                matches = []
+                for sub_klass in hierarchy['allOf']:
+                    try:
+                        if sub_klass in self.__deserializer_track:
+                            # seen it before, break the recursion
+                            matches.append(None)
+                        else:
+                            matches.append(self.__deserialize(data, sub_klass))
+                    except:  # noqa: E722
+                        pass
+                if len(matches) == len(hierarchy['allOf']):
+                    self.__deserializer_track = []
+                    return instance
+
+                # not all matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('allOf'))
+
+            if hierarchy['anyOf']:
+                for sub_klass in hierarchy['anyOf']:
+                    try:
+                        # if at least one of the sub-class matches
+                        # terminate with an instance of this class
+                        return self.__deserialize(data, sub_klass)
+                    except:  # noqa: E722
+                        pass
+                # none matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('anyOf'))
+
+            if hierarchy['oneOf']:
+                matches = []
+                for sub_klass in hierarchy['oneOf']:
+                    try:
+                        matches.append(self.__deserialize(data, sub_klass))
+                    except:  # noqa: E722
+                        pass
+                if len(matches) == 1:
+                    return matches[0]
+
+                # none matched, or more than one matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('oneOf'))
+
         if hasattr(instance, 'get_real_child_model'):
             klass_name = instance.get_real_child_model(data)
             if klass_name:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/cat.py b/samples/client/petstore/python-tornado/petstore_api/models/cat.py
index 216e5123538c..009c310a694a 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/cat.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/cat.py
@@ -38,6 +38,12 @@ class Cat(object):
         'declawed': 'declawed'
     }
 
+    composed_hierarchy = {
+        'anyOf': [],
+        'allOf': ["Animal", "CatAllOf"],
+        'oneOf': [],
+    }
+
     def __init__(self, declawed=None):  # noqa: E501
         """Cat - a model defined in OpenAPI"""  # noqa: E501
 
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/dog.py b/samples/client/petstore/python-tornado/petstore_api/models/dog.py
index c325cb252c32..fb3dc6740796 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/dog.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/dog.py
@@ -38,6 +38,12 @@ class Dog(object):
         'breed': 'breed'
     }
 
+    composed_hierarchy = {
+        'anyOf': [],
+        'allOf': ["Animal", "DogAllOf"],
+        'oneOf': [],
+    }
+
     def __init__(self, breed=None):  # noqa: E501
         """Dog - a model defined in OpenAPI"""  # noqa: E501
 
diff --git a/samples/client/petstore/python/petstore_api/api_client.py b/samples/client/petstore/python/petstore_api/api_client.py
index df3a9815aa04..683dcd2041d1 100644
--- a/samples/client/petstore/python/petstore_api/api_client.py
+++ b/samples/client/petstore/python/petstore_api/api_client.py
@@ -77,6 +77,7 @@ def __init__(self, configuration=None, header_name=None, header_value=None,
         self.cookie = cookie
         # Set default User-Agent.
         self.user_agent = 'OpenAPI-Generator/1.0.0/python'
+        self.__deserializer_track = []
 
     def __del__(self):
         if self._pool:
@@ -261,6 +262,7 @@ def __deserialize(self, data, klass):
         """
         if data is None:
             return None
+        self.__deserializer_track.append(klass)
 
         if type(klass) == str:
             if klass.startswith('list['):
@@ -633,6 +635,60 @@ def __deserialize_model(self, data, klass):
 
         instance = klass(**kwargs)
 
+        if hasattr(instance, 'composed_hierarchy'):
+            hierarchy = instance.composed_hierarchy
+            if sum([1 if v else 0 for v in hierarchy.values()]) > 1:
+                # ignore implicit AllOf
+                return instance
+
+            def error_msg(composed):
+                return "Failed to parse `{0}` as {1} ({2} {3})" \
+                    .format(data, klass,
+                            composed,
+                            ' '.join(hierarchy[composed]))
+
+            if hierarchy['allOf']:
+                matches = []
+                for sub_klass in hierarchy['allOf']:
+                    try:
+                        if sub_klass in self.__deserializer_track:
+                            # seen it before, break the recursion
+                            matches.append(None)
+                        else:
+                            matches.append(self.__deserialize(data, sub_klass))
+                    except:  # noqa: E722
+                        pass
+                if len(matches) == len(hierarchy['allOf']):
+                    self.__deserializer_track = []
+                    return instance
+
+                # not all matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('allOf'))
+
+            if hierarchy['anyOf']:
+                for sub_klass in hierarchy['anyOf']:
+                    try:
+                        # if at least one of the sub-class matches
+                        # terminate with an instance of this class
+                        return self.__deserialize(data, sub_klass)
+                    except:  # noqa: E722
+                        pass
+                # none matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('anyOf'))
+
+            if hierarchy['oneOf']:
+                matches = []
+                for sub_klass in hierarchy['oneOf']:
+                    try:
+                        matches.append(self.__deserialize(data, sub_klass))
+                    except:  # noqa: E722
+                        pass
+                if len(matches) == 1:
+                    return matches[0]
+
+                # none matched, or more than one matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('oneOf'))
+
         if hasattr(instance, 'get_real_child_model'):
             klass_name = instance.get_real_child_model(data)
             if klass_name:
diff --git a/samples/client/petstore/python/petstore_api/models/cat.py b/samples/client/petstore/python/petstore_api/models/cat.py
index 216e5123538c..009c310a694a 100644
--- a/samples/client/petstore/python/petstore_api/models/cat.py
+++ b/samples/client/petstore/python/petstore_api/models/cat.py
@@ -38,6 +38,12 @@ class Cat(object):
         'declawed': 'declawed'
     }
 
+    composed_hierarchy = {
+        'anyOf': [],
+        'allOf': ["Animal", "CatAllOf"],
+        'oneOf': [],
+    }
+
     def __init__(self, declawed=None):  # noqa: E501
         """Cat - a model defined in OpenAPI"""  # noqa: E501
 
diff --git a/samples/client/petstore/python/petstore_api/models/dog.py b/samples/client/petstore/python/petstore_api/models/dog.py
index c325cb252c32..fb3dc6740796 100644
--- a/samples/client/petstore/python/petstore_api/models/dog.py
+++ b/samples/client/petstore/python/petstore_api/models/dog.py
@@ -38,6 +38,12 @@ class Dog(object):
         'breed': 'breed'
     }
 
+    composed_hierarchy = {
+        'anyOf': [],
+        'allOf': ["Animal", "DogAllOf"],
+        'oneOf': [],
+    }
+
     def __init__(self, breed=None):  # noqa: E501
         """Dog - a model defined in OpenAPI"""  # noqa: E501
 
diff --git a/samples/client/petstore/python/tests/test_deserialization.py b/samples/client/petstore/python/tests/test_deserialization.py
index 6c4e083d1cd7..a1d9c018068c 100644
--- a/samples/client/petstore/python/tests/test_deserialization.py
+++ b/samples/client/petstore/python/tests/test_deserialization.py
@@ -85,7 +85,7 @@ def test_deserialize_dict_str_dog(self):
                 "id": 0,
                 "className": "Dog",
                 "color": "white",
-                "bread": "Jack Russel Terrier"
+                "breed": "Jack Russel Terrier"
             }
         }
         response = MockResponse(data=json.dumps(data))
diff --git a/samples/openapi3/client/petstore/python/petstore_api/api_client.py b/samples/openapi3/client/petstore/python/petstore_api/api_client.py
index df3a9815aa04..683dcd2041d1 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/api_client.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/api_client.py
@@ -77,6 +77,7 @@ def __init__(self, configuration=None, header_name=None, header_value=None,
         self.cookie = cookie
         # Set default User-Agent.
         self.user_agent = 'OpenAPI-Generator/1.0.0/python'
+        self.__deserializer_track = []
 
     def __del__(self):
         if self._pool:
@@ -261,6 +262,7 @@ def __deserialize(self, data, klass):
         """
         if data is None:
             return None
+        self.__deserializer_track.append(klass)
 
         if type(klass) == str:
             if klass.startswith('list['):
@@ -633,6 +635,60 @@ def __deserialize_model(self, data, klass):
 
         instance = klass(**kwargs)
 
+        if hasattr(instance, 'composed_hierarchy'):
+            hierarchy = instance.composed_hierarchy
+            if sum([1 if v else 0 for v in hierarchy.values()]) > 1:
+                # ignore implicit AllOf
+                return instance
+
+            def error_msg(composed):
+                return "Failed to parse `{0}` as {1} ({2} {3})" \
+                    .format(data, klass,
+                            composed,
+                            ' '.join(hierarchy[composed]))
+
+            if hierarchy['allOf']:
+                matches = []
+                for sub_klass in hierarchy['allOf']:
+                    try:
+                        if sub_klass in self.__deserializer_track:
+                            # seen it before, break the recursion
+                            matches.append(None)
+                        else:
+                            matches.append(self.__deserialize(data, sub_klass))
+                    except:  # noqa: E722
+                        pass
+                if len(matches) == len(hierarchy['allOf']):
+                    self.__deserializer_track = []
+                    return instance
+
+                # not all matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('allOf'))
+
+            if hierarchy['anyOf']:
+                for sub_klass in hierarchy['anyOf']:
+                    try:
+                        # if at least one of the sub-class matches
+                        # terminate with an instance of this class
+                        return self.__deserialize(data, sub_klass)
+                    except:  # noqa: E722
+                        pass
+                # none matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('anyOf'))
+
+            if hierarchy['oneOf']:
+                matches = []
+                for sub_klass in hierarchy['oneOf']:
+                    try:
+                        matches.append(self.__deserialize(data, sub_klass))
+                    except:  # noqa: E722
+                        pass
+                if len(matches) == 1:
+                    return matches[0]
+
+                # none matched, or more than one matched -> error
+                raise rest.ApiException(status=0, reason=error_msg('oneOf'))
+
         if hasattr(instance, 'get_real_child_model'):
             klass_name = instance.get_real_child_model(data)
             if klass_name:
diff --git a/samples/openapi3/client/petstore/python/petstore_api/models/cat.py b/samples/openapi3/client/petstore/python/petstore_api/models/cat.py
index 216e5123538c..009c310a694a 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/models/cat.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/models/cat.py
@@ -38,6 +38,12 @@ class Cat(object):
         'declawed': 'declawed'
     }
 
+    composed_hierarchy = {
+        'anyOf': [],
+        'allOf': ["Animal", "CatAllOf"],
+        'oneOf': [],
+    }
+
     def __init__(self, declawed=None):  # noqa: E501
         """Cat - a model defined in OpenAPI"""  # noqa: E501
 
diff --git a/samples/openapi3/client/petstore/python/petstore_api/models/dog.py b/samples/openapi3/client/petstore/python/petstore_api/models/dog.py
index c325cb252c32..fb3dc6740796 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/models/dog.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/models/dog.py
@@ -38,6 +38,12 @@ class Dog(object):
         'breed': 'breed'
     }
 
+    composed_hierarchy = {
+        'anyOf': [],
+        'allOf': ["Animal", "DogAllOf"],
+        'oneOf': [],
+    }
+
     def __init__(self, breed=None):  # noqa: E501
         """Dog - a model defined in OpenAPI"""  # noqa: E501