title: How to update SalesForce object values to null in CastIron orchestration
body: <p>We are using IBM WebSphere CastIron to integrate SalesForce with external systems. It works ok. 
  However I can't seem to be able to set fields to null in an update/upsert operation. Do you know any way  to do this?</p>
  
  <p>In Apex there is a fieldsToNull string property to specify the fields, however it seems like the CastIron connector doesn't support this. </p>
  
  <p>Assigning null to the field does nothing - it is documented in SF API, but I was hoping CastIron will do magic here. </p>
  
  <p>Anyone has any suggestion?</p>