code: public function process(ContainerBuilder $container)
      {
          if (!$container->hasDefinition('fxp_block.twig.extension')) {
              return;
          }
  
          $definition = $container->getDefinition('fxp_block.twig.extension');
  
          $aliases = [];
  
          foreach ($container->findTaggedServiceIds('fxp_block.type') as $serviceId => $tag) {
              $serviceDefinition = $container->getDefinition($serviceId);
              $class = $serviceDefinition->getClass();
              $alias = isset($tag[0]['template_alias'])
                  ? $tag[0]['template_alias']
                  : StringUtil::fqcnToBlockPrefix($class, true);
              $aliases[$alias] = $class;
          }
  
          $definition->replaceArgument(4, $aliases);
      }
docs: {@inheritdoc}