A question about some behavior I am seeing

[Shawn Heisey]

In SolrJ 4.7.2, if an atomic update request is sent with some fields set 
to null (the object, not the string), then those fields will be ignored 
when processing the atomic update -- no change.

In SolrJ 9, a field set to null in an atomic update request will be 
removed from the document.

This is client behavior.  The server behavior is the same whether it's 
Solr 4 or Solr 9.

Which behavior is correct?  I would guess SolrJ 9, but I want to make 
sure so I know whether to open an issue or not.

Thanks,
Shawn