added license information

Change-Id: Ia2b7f5078ed4af54e4acef7628abd3e64f098765
updated license information

Change-Id: I4dc5191c622310dfbf9a727a9274418a07e86d13
Fixed: sometimes the returned set was not unmodifiable

Change-Id: Ifb40f5389766576cf0cae272e5237bd0501592d8
Merge "Fixed: sometimes the returned set was not unmodifiable"