@property
    def extra_fields(self):
        return []
Return a pair condition used for joining and subquery pushdown. The
dataset/ETHPy150Open dimagi/commcare-hq/corehq/apps/export/forms.py/BaseFilterExportDownloadForm.extra_fields--crossover with--dataset/ETHPy150Open django/django/django/db/models/fields/related.py/ForeignObject.get_extra_restriction