This is just reminder to think about this usecase:

(See issue 31772 for more details.) The xml/core
module creates TopComponent and serialize it. The
created settings file is bound to xml/core module.
So far so good.

The problem is that this TopComponent is
CloneableEditor and serializing CloneableEditor
will serialize also CloneableOpenSupport and its
Env. But Env in case of xml/core TopComponent is
from different module - it is from xml/tree. And
if xml/tree is disabled and xml/core is enabled
the settings infrastructure will try to
deserialize this settings what will result in
ClassNotFound exception.