is there a way to create a connection that ends on another connection
(for example, to be able to attach a note to an association)?
As far as I can see, you can add anchors to a connection, but that's of
no use because the ConnectionEditParts don't have an appropriate edit
policy like ShapeEditParts, which creates commands to call the
corresponding ICreateConnectionFeature to complete the connection.
you are right: our model allows to express
that a connection has an anchor and that a connection
can be connected directly to a connection, but
the rendering engine does not support this as of now.
We plan to enable the scenario in the future.