A function to run before the given edge is detached from the given source vertex. If this method returns false, the
detach will be aborted. The difference between this and beforeDetach is that this method is fired as soon as a user
tries to detach an edge from an endpoint in the UI, whereas beforeDetach allows a user to detach the edge in the UI.
A function to run before the given edge is detached from the given source vertex. If this method returns false, the detach will be aborted. The difference between this and
beforeDetachis that this method is fired as soon as a user tries to detach an edge from an endpoint in the UI, whereasbeforeDetachallows a user to detach the edge in the UI.