https://github.com/apache/airflow/blob/main/airflow/dag_processing/manager.py#L773
"""Refresh file paths from dag dir if we haven't done it for too long."""
        now = timezone.utcnow()
        elapsed_time_since_refresh = (now - self.last_dag_dir_refresh_time).total_seconds()
        if elapsed_time_since_refresh > self.dag_dir_list_interval:
            
            self.log.info("Searching for files in %s", self._dag_directory)
            self._file_paths = list_py_file_paths(self._dag_directory)
            self.last_dag_dir_refresh_time = now
            self.log.info("There are %s files in %s", len(self._file_paths), self._dag_directory)
            self.set_file_paths(self._file_paths)
            try:
                self.log.debug("Removing old import errors")
                self.clear_nonexistent_import_errors()
            except Exception: