public Optional<String> getAuthorizer(ToShapeId service, ToShapeId shape) {
        return Optional.ofNullable(authorizers.get(service.toShapeId()))
                .flatMap(mappings -> Optional.ofNullable(mappings.get(shape.toShapeId())));
    }
Gets the effective authorizer name of a specific resource or operation
within a service.

@param service Service shape to query.
@param shape Resource or operation shape ID to query.
@return Returns the optionally resolved authorizer name.
smithy-aws-apigateway-traits/src/main/java/software/amazon/smithy/aws/apigateway/traits/AuthorizerIndex.java