cx-newsletter/components/10-rest_register.php

<?php

namespace cx_newsletter;
use \register_rest_route;

class rest_register 
implements rest_register_interface {
    public function __construct(string $namespace) {
        $this->namespace = $namespace;
    }

    public function register(rest_endpoint $endpoint) : self {
        $parameters = [
            'methods' => $endpoint->get_method(),
            'callback' => [$endpoint, 'action']
        ];

        register_rest_route(
            $this->get_namespace(),
            $endpoint->get_route(),
            $parameters
        );

        return $this;
    }   

    public function get_namespace() : string {
        return $this->namespace;
    }

    private string $namespace;
}