during indexing select only those fields that have content
during indexing select only those fields that have content

to solve the problem with null_values during indexing of .suggest fields

1000miles/speakerinnen_liste,1000miles/speakerinnen_liste,rubymonsters/speakerinnen_liste,rubymonsters/speakerinnen_liste,rubymonsters/speakerinnen_liste,1000miles/speakerinnen_liste