Issue #3256822: StreamWrapperManager Service has public methods not on interface

Closes #3256822

core/lib/Drupal/Core/StreamWrapper/CoreStreamWrapperManagerInterface.php

+<?php
+
+namespace Drupal\Core\StreamWrapper;
+
+/**
+ * Provides StreamWrapper manager methods utilized by Core.
+ *
+ * @see \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface
+ *
+ * @internal
+ *   These methods are necessary for a StreamWrapper manager to implement
+ *   however unlike methods on StreamWrapperManagerInterface these methods
+ *   generally should only be invoked by Drupal Core and not third parties.
+ */
+interface CoreStreamWrapperManagerInterface {
+
+  /**
+   * Adds a stream wrapper.
+   *
+   * @param string $service_id
+   *   The service id.
+   * @param string $class
+   *   The stream wrapper class.
+   * @param string $scheme
+   *   The scheme for which the wrapper should be registered.
+   */
+  public function addStreamWrapper(string $service_id, string $class, string $scheme): void;
+
+  /**
+   * Registers the tagged stream wrappers.
+   */
+  public function register(): void;
+
+  /**
+   * Un-registers the tagged stream wrappers.
+   */
+  public function unregister(): void;
+
+}