@classmethod
def DeregisterCredentials(cls, credentials):
    """Deregisters a path specification credentials.

    Args:
      credentials (Credentials): credentials.

    Raises:
      KeyError: if credential object is not set for the corresponding
          type indicator.
    """
    if credentials.type_indicator not in cls._credentials:
        raise KeyError('Credential object not set for type indicator: {0:s}.'
            .format(credentials.type_indicator))
    del cls._credentials[credentials.type_indicator]
