code: def _auto_client_files(cls, client, ca_path=None, ca_contents=None, cert_path=None,
                             cert_contents=None, key_path=None, key_contents=None):
          
          files = []
          if ca_path and ca_contents:
              client['ca'] = ca_path
              files.append(dict(path=ca_path,
                                contents=ca_contents,
                                mode=DEFAULT_FILE_MODE))
          if cert_path and cert_contents:
              client['cert'] = cert_path
              files.append(dict(path=cert_path,
                                contents=cert_contents,
                                mode=DEFAULT_FILE_MODE))
          if key_path and key_contents:
              client['key'] = key_path
              files.append(dict(path=key_path,
                                contents=key_contents,
                                mode=DEFAULT_FILE_MODE,))
          return files
docs: returns a list of NetJSON extra files for automatically generated clients
          produces side effects in ``client`` dictionary