How to use the conan.MANIFEST_JSON_FILE function in conan

'6a630e46a580e8b2327fc45d9d1f4734ccaeb0afaa094e0f45722a5f1c91e009/layer.tar',
                 ]
             'RepoTags': ['user/image:version'],
             "Parent": "sha256:5a00e6ccb81ef304e1bb9995ea9605f199aa96659a44237d58ca96982daf9af8"
             },

            {'Config': '7043867122e704683c9eaccd7e26abcd5bc9fea413ddfeae66166697bdcbde1f.json',
             'Layers': [
                 '768d4f50f65f00831244703e57f64134771289e3de919a576441c9140e037ea2/layer.tar',
                 '6a630e46a580e8b2327fc45d9d1f4734ccaeb0afaa094e0f45722a5f1c91e009/layer.tar',
                 ]
             'RepoTags': ['user/image:version']
             },
        ]
        """
        manifest_file = join(repo_dir, MANIFEST_JSON_FILE)
        manifest = load_json(manifest_file)

        for image_config in manifest:
            config_file = image_config.get('Config')

            config_file = join(repo_dir, config_file)
            if not exists(config_file):
                # FIXME: orphaned manifest entry
                image_id = file_base_name(config_file)
                image = Image(image_id=image_id)
                assert image.image_id not in self.images_by_id
                self.images_by_id[image.image_id] = image
                continue

            image = Image.load_image_config(config_file)
            assert image.image_id not in self.images_by_id

def populate(self, base_dir):
        """
        Collect the `base_dir` for image repositories.
        """
        for fil in fileutils.file_iter(base_dir):
            # FIXME: we are only looking at V11 repos for now.
            fn = fileutils.file_name(fil)
            if not fn == MANIFEST_JSON_FILE:
                continue
            rd = parent_directory(fil)
            repo = Repository()
            repo.load_manifest(rd)
            logger_debug('populate: path: %(fn)r' % locals())
            self.repositories[rd] = repo