Whether this change is generic or contains specific information about the change.
By default ChangeEmitters contained in this library don't contain
specific information about a change (except for the Change.quiet value)
and instead recycle the same Change object on each change
to minimize garbage collection.
Whether a change will trigger a parent EmitterContainer to notify its listeners that it has changed.
This can be useful if you want to batch changes to children of a EmitterContainer but have
the container only emit one change.