namespace Drupalmy_module;

use DrupalCoreDependencyInjectionContainerBuilder;
use DrupalCoreDependencyInjectionServiceProviderBase;

// @note: You only need Reference, if you want to change service arguments.
use SymfonyComponentDependencyInjectionReference;

/**
 * Modifies the mail provider service.
 */
class MyModuleServiceProvider extends ServiceProviderBase {

  /**
   * {@inheritdoc}
   */
  public function alter(ContainerBuilder $container) {
    $definition = $container->getDefinition('plugin.manager.mail');
    $definition->setClass('DrupalMY_MODULEMyMailProvider');
  }
}