LPS-49255 Fix tests
LPS-49255 Preserve collection invariant: c.add(e) => c.contains(e)

http://docs.oracle.com/javase/7/docs/api/java/util/Collection.html#add(E)

As far as I understand from the documentation a list is not allowed to
return false in the add(E e) method unless it is a list that does not
allow duplicate elements and the element being inserted is already
present in the list. Although a list is entitled to prevent an element
from being inserted it MUST do so by throwing an exception to preserve
this invariant.
LPS-49255 Update tests to reflect the new behaviour
LPS-49255 SF