Generate unserviceable swagger server code while object include object define

Description

After I suggessfully generate the swagger server code for python-flask, the code cannot be run. The root cause is the generated code by swagger include a wrong class name.

Yaml:
clusterStatsResultType:
type: object
properties:
hwMetrics:
type: object
properties:
metricsNum:
type: number
description: how many metrics to be record such as cpu, gpu and memory, and then, the value is 3
metricsList:
type: array
description: it shall be current value such as current cpu number, or memory size, gpu number, node number and total job number
items:
$ref: '#/definitions/keyValuePair'

The generated code as:
class ClusterStatsResultType(Model):
"""NOTE: This class is auto generated by the swagger code generator program.

Do not edit the class manually.
"""

def __init__(self, hw_metrics: ClusterStatsResultTypeHwMetrics=None, user_metrics: List[UserResourceType]=None):  # noqa: E501
    """ClusterStatsResultType - a model defined in Swagger

    :param hw_metrics: The hw_metrics of this ClusterStatsResultType.  # noqa: E501
    :type hw_metrics: ClusterStatsResultTypeHwMetrics
    :param user_metrics: The user_metrics of this ClusterStatsResultType.  # noqa: E501
    :type user_metrics: List[UserResourceType]
    """
    self.swagger_types = {
        'hw_metrics': ClusterStatsResultTypeHwMetrics,
        'user_metrics': List[UserResourceType]
    }

There are two issues:

1. ClusterStatsResultTypeHwMetrics is not right object name and there is no any HwMetrics related define generated
2. UserResourceType object has been generated. But not correctly imported in the model file.

Swagger-codegen version

I run the generate from Swagger web server.

Swagger declaration file content or url

Command line used for generation

Steps to reproduce

Related issues/PRs

Suggest a fix/enhancement