private static String getNullableAuthorizerValue(Shape shape, String previous) {
        return shape.getTrait(AuthorizerTrait.class).map(AuthorizerTrait::getValue).orElse(previous);
    }
Mapping of service shapes to a authorizer traits.
smithy-aws-apigateway-traits/src/main/java/software/amazon/smithy/aws/apigateway/traits/AuthorizerIndex.java