Change record status: 
Project: 
Introduced in branch: 
8.2.x
Introduced in version: 
8.2.0-rc2
Description: 

Configuration may need to be merged into a migration plugin at runtime (for example, in the Drupal upgrade path setting source_base_path for file migrations). This has been more complex than necessary - it may now be done more straightforwardly by providing an array of configuration overrides to MigrationPluginManager::createInstance().

Before:

$migration = \Drupal::service('plugin.manager.migration')->createInstance('d6_file');
$source = $migration->getSourceConfiguration();
$source['constants']['source_base_path'] = $source_base_path;
$migration->set('source', $source);

After:

$configuration['source']['constants']['source_base_path'] = $source_base_path;
$migration = \Drupal::service('plugin.manager.migration')->createInstance('d6_file', $configuration);
Impacts: 
Module developers
Updates Done (doc team, etc.)
Online documentation: 
Not done
Theming guide: 
Not done
Module developer documentation: 
Not done
Examples project: 
Not done
Coder Review: 
Not done
Coder Upgrade: 
Not done
Other: 
Other updates done