Merge pull request #11 from jkonecki/Fix_for_warning_CS0472

Fix for warning CS0472: The result of the expression is always 'false' -- Guid is a struct, so can never be null.

Author: jthelin

src/Orleans/Streams/SimpleMessageStream/SimpleMessageStreamProvider.cs

@@ -63,9 +63,6 @@ public Task Start()
 
         public IAsyncStream<T> GetStream<T>(Guid id, string streamNamespace)
         {
-            if (id == null)
-                throw new ArgumentNullException("id");
-
             var streamId = StreamId.GetStreamId(id, Name, streamNamespace);
             return providerRuntime.GetStreamDirectory().GetOrAddStream<T>(
                 streamId,

src/OrleansRuntime/Streams/PersistentStream/PersistentStreamProvider.cs

@@ -119,8 +119,6 @@ public async Task Start()
 
         public IAsyncStream<T> GetStream<T>(Guid id, string streamNamespace)
         {
-            if (id == null) throw new ArgumentNullException("id");
-
             var streamId = StreamId.GetStreamId(id, Name, streamNamespace);
             return providerRuntime.GetStreamDirectory().GetOrAddStream<T>(
                 streamId, () => new StreamImpl<T>(streamId, this, IsRewindable));