Fix the null pointer exception when generating examples for schemas in python-experimental (#12019)

* Improves example generator for python-experimental

* Fixes quotes around date example

* Improves object schema examplple gen

* Samples regenerated

* Adds back in AnyType + oneOf discriminator handling

* Reverts version file

* Returns early in example gen for array composed schemas

* Adds toExampleValue method to python-exp

* Improves pattern regex sample generation in python-experimental

* Fixes comment typo

samples/openapi3/client/petstore/python-experimental/docs/FakeApi.md

@@ -766,7 +766,7 @@ with petstore_api.ApiClient(configuration) as api_client:
     api_instance = fake_api.FakeApi(api_client)
 
     # example passing only optional values
-    body = ComposedOneOfDifferentTypes()
+    body = ComposedOneOfDifferentTypes(None)
     try:
         api_response = api_instance.composed_one_of_different_types(
             body=body,
@@ -866,12 +866,12 @@ with petstore_api.ApiClient(configuration) as api_client:
         number=32.1,
         _float=3.14,
         double=67.8,
-        string="a",
-        pattern_without_delimiter="AUR,rZ#UM/?R,Fp^l6$ARjbhJk C",
+        string="A",
+        pattern_without_delimiter="Aj",
         byte='YQ==',
         binary=open('/path/to/file', 'rb'),
-        date=isoparse('1970-01-01').date(),
-        date_time=isoparse('2020-02-02T20:20:20.22222Z'),
+        date="1970-01-01",
+        date_time="2020-02-02T20:20:20.222220Z",
         password="password_example",
         callback="callback_example",
     )
@@ -911,7 +911,7 @@ Name | Type | Description | Notes
 **byte** | **str** | None | 
 **binary** | **file_type** | None | [optional] 
 **date** | **date** | None | [optional] 
-**dateTime** | **datetime** | None | [optional]  if omitted the server will use the default value of isoparse('2010-02-01T10:20:10.11111+01:00')
+**dateTime** | **datetime** | None | [optional]  if omitted the server will use the default value of 2010-02-01T10:20:10.11111+01:00
 **password** | **str** | None | [optional] 
 **callback** | **str** | None | [optional] 
 **any string name** | **bool, date, datetime, dict, float, int, list, str, none_type** | any string name can be used but the value must be the correct type | [optional]
@@ -1434,12 +1434,12 @@ with petstore_api.ApiClient(configuration) as api_client:
 
     # example passing only optional values
     query_params = {
-        'compositionAtRoot': ,
+        'compositionAtRoot': None,
         'compositionInProperty': dict(
-        some_prop=,
+        some_prop=None,
     ),
     }
-    body = 
+    body = None
     try:
         # testing composed schemas at inline locations
         api_response = api_instance.inline_composition(