IdStory Identity Manager

I have a following scenario:

I have a form attribute "description" of TEXT type. This attribute is mapped to attribute "description" of end system and the option "Send IdM value only if its not null" is checked. I go create the entity and set its form attributes, but I do not set any value for the description attribute. When I save the entity, provisioning still sends the description attribute. I suspect, that when editing the eav attributes, empty TEXT fields set values of the attributes to empty strings, therefore the "not null" filter is not effective. Isn't this a bug?