Fixed TestSetOnce tests
Fixed TestSetOnce tests

These tests expect exceptions to be thrown, so I added that requirement
as a test attribute.

zmaruo/lucenenet,mdissel/lucene.net,antiufo/lucenenet,NightOwl888/lucenenet,apache/lucenenet,NightOwl888/lucenenet,jeme/lucenenet,zmaruo/lucenenet,jpsullivan/lucenenet,sisve/lucenenet,jpsullivan/lucenenet,sisve/lucenenet,antiufo/lucenenet,jeme/lucenenet,jeme/lucenenet,apache/lucenenet,apache/lucenenet,apache/lucenenet,laimis/lucenenet,laimis/lucenenet,NightOwl888/lucenenet,mdissel/lucene.net,NightOwl888/lucenenet,jeme/lucenenet