public function testOnRemoveParentRemoveChild()
 {
     $configuration = new Configuration(eVersion::V_2_2_10());
     $parent_name = 'source1';
     $child_name = 'source2';
     $parent = $configuration->addSource($parent_name);
     $child = $configuration->addSource($child_name, $parent_name);
     $parent->delete();
     static::assertTrue($child->isDeleted());
 }