def full_init(self):
        """Load annotation file and set ``BaseDataset._fully_initialized`` to
        True."""
        super().full_init()

        #  To support the standard OpenMMLab 2.0 annotation format. Generate
        #  metainfo in internal format from standard metainfo format.
        if 'categories' in self._metainfo and 'classes' not in self._metainfo:
            categories = sorted(
                self._metainfo['categories'], key=lambda x: x['id'])
            self._metainfo['classes'] = tuple(
                [cat['category_name'] for cat in categories])
Load annotation file and set ``BaseDataset._fully_initialized`` to
        True.
mmpretrain/datasets/base_dataset.py