When using any of the deployment plan editors, setting a field to have nothing in it gives an XML tag with nothing in it. Before editing a plan, unnecessary tags are not shown in the deployment plan, this is the state the plan should revert to. For example:
If I use the editor to specify an application client call back handler, I will get a tag like this (which is good)
Going back into the editor and removing that, I get
I was expecting the whole line to just be deleted.