Emptying object selections

[theobat]

So we've come up with a situation where this:
master...theobat:empty-object-selection
Actually removes critical part of a query like:

query {
  id
  content
  test {
    id
  }
}

Would work just fine until we reach the point where the mutationHandler invalidate the query and the query is refetched. A this point cashay rebuild a query like this:

query {
  id
  content
  test
}

Which is not valid. So at first glance I decided to just properly remove the object that cashay emptied but then I realized I needed this object... What's the idea behind the comment just above the line responsible for this ?
https://github.com/mattkrick/cashay/blob/master/src/query/printMinimalQuery.js#L64

[mattkrick]

ah, that's a good catch
so the motive is payload reduction, basically create a object of everything you have locally & then remove those things. now if you don't have the id field locally, then firstField.sendToServer should be true. from the query you pasted it looks like it did a good job of removing unnecessary children, but it didn't clean up the empty parents.