Extra links supported for operators coming from third-party packages:

airflow.serialization.serialized_objects.BUILTIN_OPERATOR_EXTRA_LINKS

airflow/providers_manager.py
"""
        Finds all built-in airflow providers if airflow is run from the local sources.
        It finds `provider.yaml` files for all such providers and registers the providers using those.
        This 'provider.yaml' scanning takes precedence over scanning packages installed
        in case you have both sources and packages installed, the providers will be loaded from
        the "airflow" sources rather than from the packages.
        """
        try:
            import airflow.providers
        except ImportError:
            log.info("You have no providers installed.")
            return
        try:
            for path in airflow.providers.__path__:
                self._add_provider_info_from_local_source_files_on_path(path)
        except Exception as e:  
            log.warning("Error when loading 'provider.yaml' files from airflow sources: %s", e)
    def _add_provider_info_from_local_source_files_on_path(self, path) -> None:
        """
        Finds all the provider.yaml files in the directory specified.
        :param path: path where to look for provider.yaml files
        """
        root_path = path
        for folder, subdirs, files in os.walk(path, topdown=True):
            for filename in fnmatch.filter(files, "provider.yaml"):
                package_name = "apache-airflow-providers" + folder[len(root_path) :].replace(os.sep, "-")
                self._add_provider_info_from_local_source_file(os.path.join(folder, filename), package_name)
                subdirs[:] = []
    def _add_provider_info_from_local_source_file(self, path, package_name) -> None: