CredentialsNDBProperty from oauth2client

Question

I am replacing oauth2client as part of a google app engine upgrade. Oauth2client was deprecated. https://github.com/googleapis/oauth2client/tree/50d20532a748f18e53f7d24ccbe6647132c979a9/oauth2client

My project uses CredentialNDBProperty from this library as part of a model.

class Config(model.Base, model.ConfigAuth):

    yt_offline_creds = CredentialsNDBProperty()

Is there a suitable replacement available in google.appengine.ext or other associated libraries such as google-auth or oauthlib?

class CredentialsNDBProperty(ndb.BlobProperty):
    """App Engine NDB datastore Property for Credentials.

    Serves the same purpose as the DB CredentialsProperty, but for NDB
    models. Since CredentialsProperty stores data as a blob and this
    inherits from BlobProperty, the data in the datastore will be the same
    as in the DB case.

    Utility property that allows easy storage and retrieval of Credentials
    and subclasses.
    """

    def _validate(self, value):
        """Validates a value as a proper credentials object.

        Args:
            value: A value to be set on the property.

        Raises:
            TypeError if the value is not an instance of Credentials.
        """
        _LOGGER.info('validate: Got type %s', type(value))
        if value is not None and not isinstance(value, client.Credentials):
            raise TypeError(
                'Property {0} must be convertible to a credentials '
                'instance; received: {1}.'.format(self._name, value))

    def _to_base_type(self, value):
        """Converts our validated value to a JSON serialized string.

        Args:
            value: A value to be set in the datastore.

        Returns:
            A JSON serialized version of the credential, else '' if value
            is None.
        """
        if value is None:
            return ''
        else:
            return value.to_json()

    def _from_base_type(self, value):
        """Converts our stored JSON string back to the desired type.

        Args:
            value: A value from the datastore to be converted to the
                   desired type.

        Returns:
            A deserialized Credentials (or subclass) object, else None if
            the value can't be parsed.
        """
        if not value:
            return None
        try:
            # Uses the from_json method of the implied class of value
            credentials = client.Credentials.new_from_json(value)
        except ValueError:
            credentials = None
        return credentials