def METHOD_NAME(self, stream_config: FileBasedStreamConfig) -> AbstractSchemaValidationPolicy:
    if stream_config.validation_policy not in self.validation_policies:
        # This should never happen because we validate the config against the schema's validation_policy enum
        raise ValidationError(
            f"`validation_policy` must be one of {list(self.validation_policies.keys())}", model=FileBasedStreamConfig
        )
    return self.validation_policies[stream_config.validation_policy]