With nested api model expect is raising error with key not found.

[BHAUTIK04]

We have flask_restplus for our API, in one of the post requests we have a nested structure. When we validate input json with expect decorator it is raising the key error. API model is

user_expected_field = api.model('UserRequest', {
            "user_email": fields.String(example='user@abc.com', required=True),
            "user_name": fields.String(example="user", required=True),
            "user_gender": fields.String(example="Male", required=True),
            "user_address":fields.List(fields.Nested(api.model(
                       "AddressModel", {
                                "street1": field.String(required=True),
                                "street2": field.String(required=True),
                                "city": field.String(required=True),
                                "state": field.String(required=True),
                                "country": field.String(required=True),
                        }
            )))
        },
    )

Error:

Traceback (most recent call last):
File "/lib/python3.6/site-packages/jsonschema/validators.py", line 812, in resolve_fragment
document = document[part]
KeyError: 'AddressModel'

Any help will be highly appreciated.