Minor Description
Streaming expressions should support collection aliases.
When I tried to access collection alias I get a null pointer exception.
issue seems to be related to following code: clusterState.getActiveSlices returns null
Collection<Slice> slices = clusterState.getActiveSlices(this.collection);
fix seems to fairly simple , clusterState.getActiveSlices can be made aware of collection alias. I am not sure what will happen when we have large alias which has hundred of slices.