Return all registered Heroku Connect Models.

    Returns:
        (Iterator):
            All registered models that are subclasses of `.HerokuConnectModel`.
            Abstract models are excluded, since they are not registered.

def get_heroku_connect_models():
    """
    Return all registered Heroku Connect Models.

    Returns:
        (Iterator):
            All registered models that are subclasses of `.HerokuConnectModel`.
            Abstract models are excluded, since they are not registered.

    """
    from django.apps import apps
    apps.check_models_ready()
    from heroku_connect.db.models import HerokuConnectModel

    return (
        model
        for models in apps.all_models.values()
        for model in models.values()
        if issubclass(model, HerokuConnectModel)
        and not model._meta.managed
    )