[Bug Report] Autocomplete on clear sets variable to undefined and not null. This causes some unexpected behaviour when using nested objects as the value

[JamesDeegan]

Versions and Environment

Vuetify: 2.0.0-alpha.8
Vue: 2.6.9
Browsers: Chrome 73.0.3683.75
OS: Windows 10

Steps to reproduce

Select a supplier
delete the supplier
notice how that completely deletes the supplier key: value from the form object

Expected Behavior

I expect the value to be set to null. so, supplier: null. Not for the key value pair to be entirely deleted

Actual Behavior

because autocomplete sets the bound value to undefined and not null, its deleting the key and value pair bound to it.

Reproduction Link

https://codepen.io/anon/pen/bZKjXW

[KaelWD]

Duplicate of #5722, #4144

key value pair to be entirely deleted

It isn't, JSON just doesn't have undefined: https://codepen.io/anon/pen/mojqmg?editors=1010