reverted:
--- b/core/modules/migrate/src/Plugin/MigrationProviderInterface.php
+++ /dev/null
@@ -1,20 +0,0 @@
-<?php
-
-namespace Drupal\migrate\Plugin;
-
-/**
- * An interface to get the plugin provider.
- */
-interface MigrationProviderInterface {
-
-  /**
-   * Gets the plugin provider.
-   *
-   * @return string|null
-   *   The plugin provider or NULL if a provider is not found. Note that for a
-   *   source plugin the provider is expected to be the name of the extension in
-   *   the source database.
-   */
-  public function getMigrationProvider();
-
-}
diff -u b/core/modules/migrate/src/Plugin/migrate/destination/Config.php b/core/modules/migrate/src/Plugin/migrate/destination/Config.php
--- b/core/modules/migrate/src/Plugin/migrate/destination/Config.php
+++ b/core/modules/migrate/src/Plugin/migrate/destination/Config.php
@@ -198,7 +198,7 @@
   /**
    * {@inheritdoc}
    */
-  public function getMigrationProvider() {
+  public function getDestinationModule() {
     if (!empty($this->configuration['destination_module'])) {
       return $this->configuration['destination_module'];
     }
diff -u b/core/modules/migrate/src/Plugin/migrate/destination/DestinationBase.php b/core/modules/migrate/src/Plugin/migrate/destination/DestinationBase.php
--- b/core/modules/migrate/src/Plugin/migrate/destination/DestinationBase.php
+++ b/core/modules/migrate/src/Plugin/migrate/destination/DestinationBase.php
@@ -8,7 +8,6 @@
 use Drupal\migrate\Plugin\MigrateDestinationInterface;
 use Drupal\migrate\Plugin\MigrateIdMapInterface;
 use Drupal\migrate\Plugin\RequirementsInterface;
-use Drupal\migrate\Plugin\MigrationProviderInterface;
 
 /**
  * Base class for migrate destination classes.
@@ -20,7 +19,7 @@
  *
  * @ingroup migration
  */
-abstract class DestinationBase extends PluginBase implements MigrateDestinationInterface, RequirementsInterface, MigrationProviderInterface {
+abstract class DestinationBase extends PluginBase implements MigrateDestinationInterface, RequirementsInterface {
 
   /**
    * Indicates whether the destination can be rolled back.
@@ -114,7 +113,7 @@
   /**
    * {@inheritdoc}
    */
-  public function getMigrationProvider() {
+  public function getDestinationModule() {
     if (!empty($this->configuration['destination_module'])) {
       return $this->configuration['destination_module'];
     }
diff -u b/core/modules/migrate/src/Plugin/migrate/source/SourcePluginBase.php b/core/modules/migrate/src/Plugin/migrate/source/SourcePluginBase.php
--- b/core/modules/migrate/src/Plugin/migrate/source/SourcePluginBase.php
+++ b/core/modules/migrate/src/Plugin/migrate/source/SourcePluginBase.php
@@ -11,7 +11,6 @@
 use Drupal\migrate\Plugin\MigrateIdMapInterface;
 use Drupal\migrate\Plugin\MigrateSourceInterface;
 use Drupal\migrate\Row;
-use Drupal\migrate\Plugin\MigrationProviderInterface;
 
 /**
  * The base class for all source plugins.
@@ -23,7 +22,7 @@
  *
  * @ingroup migration
  */
-abstract class SourcePluginBase extends PluginBase implements MigrateSourceInterface, RollbackAwareInterface, MigrationProviderInterface {
+abstract class SourcePluginBase extends PluginBase implements MigrateSourceInterface, RollbackAwareInterface {
 
   /**
    * The module handler service.
@@ -545,7 +544,7 @@
   /**
    * {@inheritdoc}
    */
-  public function getMigrationProvider() {
+  public function getSourceModule() {
     if (!empty($this->configuration['source_module'])) {
       return $this->configuration['source_module'];
     }
diff -u b/core/modules/migrate/tests/src/Kernel/Plugin/MigrationProvidersExistTest.php b/core/modules/migrate/tests/src/Kernel/Plugin/MigrationProvidersExistTest.php
--- b/core/modules/migrate/tests/src/Kernel/Plugin/MigrationProvidersExistTest.php
+++ b/core/modules/migrate/tests/src/Kernel/Plugin/MigrationProvidersExistTest.php
@@ -5,7 +5,6 @@
 Use Drupal\Component\Render\FormattableMarkup;
 use Drupal\KernelTests\FileSystemModuleDiscoveryDataProviderTrait;
 use Drupal\Tests\migrate_drupal\Kernel\MigrateDrupalTestBase;
-use Drupal\migrate\Plugin\MigrationProviderInterface;
 
 /**
  * Tests that modules exist for all source and destination plugins.
@@ -41,16 +40,8 @@
     $this->assertTrue(array_key_exists('migration_provider_no_annotation', $migrations));
     /** @var \Drupal\migrate\Plugin\Migration $migration */
     foreach ($migrations as $migration) {
-      $source_module = NULL;
-      $destination_module = NULL;
-      $source_plugin = $migration->getSourcePlugin();
-      if ($source_plugin instanceof MigrationProviderInterface) {
-        $source_module = $source_plugin->getMigrationProvider();
-      }
-      $destination_plugin = $migration->getDestinationPlugin();
-      if ($destination_plugin instanceof MigrationProviderInterface) {
-        $destination_module = $destination_plugin->getMigrationProvider();
-      }
+      $source_module = $migration->getSourcePlugin()->getSourceModule();
+      $destination_module = $migration->getDestinationPlugin()->getDestinationModule();
       $migration_id = $migration->getPluginId();
       if ($migration_id == 'migration_provider_test') {
         $this->assertFalse($source_module, new FormattableMarkup('Source module not found for @migration_id.', ['@migration_id' => $migration_id]));
diff -u b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
--- b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
+++ b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
@@ -9,7 +9,6 @@
 use Drupal\Core\State\StateInterface;
 use Drupal\Core\Url;
 use Drupal\migrate\Plugin\MigrationPluginManagerInterface;
-use Drupal\migrate\Plugin\MigrationProviderInterface;
 use Drupal\migrate_drupal_ui\Batch\MigrateUpgradeImportBatch;
 use Drupal\migrate_drupal\MigrationConfigurationTrait;
 use Symfony\Component\DependencyInjection\ContainerInterface;
@@ -447,21 +446,11 @@
     $table_data = [];
     foreach ($migrations as $migration) {
       $migration_id = $migration->getPluginId();
-
-      $source_module = NULL;
-      $source_plugin = $migration->getSourcePlugin();
-      if ($source_plugin instanceof MigrationProviderInterface) {
-        $source_module = $source_plugin->getMigrationProvider();
-      }
+      $source_module = $migration->getSourcePlugin()->getSourceModule();
       if (!$source_module) {
         drupal_set_message($this->t('Source module not found for @migration_id.', ['@migration_id' => $migration_id]), 'error');
       }
-
-      $destination_module = NULL;
-      $destination_plugin = $migration->getDestinationPlugin();
-      if ($destination_plugin instanceof MigrationProviderInterface) {
-        $destination_module = $destination_plugin->getMigrationProvider();
-      }
+      $destination_module = $migration->getDestinationPlugin()->getDestinationModule();
       if (!$destination_module) {
         drupal_set_message($this->t('Destination module not found for @migration_id.', ['@migration_id' => $migration_id]), 'error');
       }
only in patch2:
unchanged:
--- a/core/modules/migrate/src/Plugin/MigrateDestinationInterface.php
+++ b/core/modules/migrate/src/Plugin/MigrateDestinationInterface.php
@@ -133,4 +133,11 @@ public function supportsRollback();
    */
   public function rollbackAction();
 
+  /**
+   * Gets the destination module handling the destination data.
+   *
+   * @return string|null
+   *   The destination module or NULL if not found.
+   */
+  public function getDestinationModule();
 }
only in patch2:
unchanged:
--- a/core/modules/migrate/src/Plugin/MigrateSourceInterface.php
+++ b/core/modules/migrate/src/Plugin/MigrateSourceInterface.php
@@ -100,4 +100,12 @@ public function __toString();
    */
   public function getIds();
 
+  /**
+   * Gets the source module providing the source data.
+   *
+   * @return string|null
+   *   The source module or NULL if not found.
+   */
+  public function getSourceModule();
+
 }