dCommon.

Args:
  common_type: base._Common, The actual loaded user written command or group
    class.
  path: [str], A list of group names that got us down to this command group
    with respect to the CLI itself.  This path should be used for things
    like error reporting when a specific element in the tree needs to be
    referenced.
  release_track: base.ReleaseTrack, The release track (ga, beta, alpha,
    preview) that this command group is in.  This will apply to all commands
    under it.
  cli_generator: cli.CLILoader, The builder used to generate this CLI.
  parser_group: argparse.Parser, The parser that this command or group will
    live in.
  allow_positional_args: bool, True if this command can have positional
    arguments.
  parent_group: CommandGroup, The parent of this command or group. None if
    at the root.
