<?php
\Cake\Datasource\FactoryLocator::add('Endpoint', [Muffin\Webservice\Model\EndpointRegistry::class, 'get']);

<?php
use Cake\Datasource\FactoryLocator;
use Muffin\Webservice\Model\EndpointLocator;

FactoryLocator::add('Endpoint', [new EndpointLocator(), 'get']);

Use EndpointLocator instead of EndpointRegistry.
Use EndpointLocator instead of EndpointRegistry.
