Checks to be sure the changeset is known by the journal

def _validate_changeset(self, changeset_id: uuid.UUID) -> None:
        """
        Checks to be sure the changeset is known by the journal
        """
        if not self.journal.has_changeset(changeset_id):
            raise ValidationError("Changeset not found in journal: {0}".format(
                str(changeset_id)
            ))