The versions of plug-ins and fragments should be synchronized with the version of the packaged feature so that you can manage plug-in, fragment, and feature versions consistently. Developers typically ignore individual manifest versions until it is time to deploy their features. The Update Manager uses feature versions to determine whether a plug-in is older or newer than one already installed. Plug-ins and fragments need to follow the same version number conventions so there is no confusion about which plug-in version belongs to which feature version.
The most convenient way to synchronize versions is to pick the version of the feature and force it into all the plug-ins and fragments that the feature references. This operation updates manifest files, so you are required to close all the manifest editors before proceeding.
We will take our ongoing example and force the feature version (1.2.2) into "XYZ Plug-in" and "German Fragment."