[python] valid swagger input results in unusable python client

Description

I'm attempting to use swagger-codegen to create a python client for the the following swagger input: swagger.json.txt. The resulting client is unable to be imported into a python repl:

In [2]: from swagger_client.api_client import ApiClient
---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
<ipython-input-2-f419a6e2dcad> in <module>()
----> 1 from swagger_client.api_client import ApiClient

~/Code/python_cloud_client/client/swagger_client/__init__.py in <module>()
     17
     18 # import apis into sdk package
---> 19 from swagger_client.api.authentication_api import AuthenticationApi
     20 from swagger_client.api.clusters_elasticsearch_api import ClustersElasticsearchApi
     21 from swagger_client.api.clusters_kibana_api import ClustersKibanaApi

~/Code/python_cloud_client/client/swagger_client/api/__init__.py in <module>()
      4
      5 # import apis into api package
----> 6 from swagger_client.api.authentication_api import AuthenticationApi
      7 from swagger_client.api.clusters_elasticsearch_api import ClustersElasticsearchApi
      8 from swagger_client.api.clusters_kibana_api import ClustersKibanaApi

~/Code/python_cloud_client/client/swagger_client/api/authentication_api.py in <module>()
     19 import six
     20
---> 21 from swagger_client.api_client import ApiClient
     22
     23

~/Code/python_cloud_client/client/swagger_client/api_client.py in <module>()
     25
     26 from swagger_client.configuration import Configuration
---> 27 import swagger_client.models
     28 from swagger_client import rest
     29

~/Code/python_cloud_client/client/swagger_client/models/__init__.py in <module>()
     27 from swagger_client.models.basic_failed_reply import BasicFailedReply
     28 from swagger_client.models.basic_failed_reply_element import BasicFailedReplyElement
---> 29 from swagger_client.models.bool_query import BoolQuery
     30 from swagger_client.models.capacity_constraints_resource import CapacityConstraintsResource
     31 from swagger_client.models.change_source_info import ChangeSourceInfo

~/Code/python_cloud_client/client/swagger_client/models/bool_query.py in <module>()
     17 import six
     18
---> 19 from swagger_client.models.query_container import QueryContainer  # noqa: F401,E501
     20
     21

~/Code/python_cloud_client/client/swagger_client/models/query_container.py in <module>()
     17 import six
     18
---> 19 from swagger_client.models.bool_query import BoolQuery  # noqa: F401,E501
     20 from swagger_client.models.exists_query import ExistsQuery  # noqa: F401,E501
     21 from swagger_client.models.match_query import MatchQuery  # noqa: F401,E501

ImportError: cannot import name 'BoolQuery'

Swagger-codegen version

I've attempted to use the stable 2.3.1, as well as 2.4.0-20181023.093755-340, with the same issue.

Swagger declaration file content or url

Also linked above: swagger.json.txt

Command line used for generation

java -jar swagger-codegen-client.jar generate \
  -i swagger.json \
  -l python \
  -o python-ece-client

Steps to reproduce

1. Generate the client using the command above
2. Go into python REPL
3. Attempt to import the API client from swagger_client.api_client import ApiClient

Related issues/PRs

I wasn't able to locate anything

Suggest a fix/enhancement

From what I can tell from the generated code, it appears that there might be some circular references that throw it off - for example in this case, BoolQuery has a QueryContainer which has a BoolQuery.

Let me know if I can provide anything else that might be helpful!

Start with the linked swagger.json.txt and reproduce the command using the Python generator. Inspect the generated swagger_client/models/bool_query.py and query_container.py files, then verify that from swagger_client.api_client import ApiClient imports successfully without the circular-reference failure.