Returns a new batch injector

def _create_injector(self, injector):
        """Returns a new batch injector"""
        if injector == "block_info":
            block_info_injector = importlib.import_module(
                "sawtooth_validator.journal.block_info_injector")

            return block_info_injector.BlockInfoInjector(
                self._state_view_factory, self._signer)

        raise UnknownBatchInjectorError(injector)