Ticket 7832

[Form] deprecated "property_path" in favor of "map_to"

 Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | yes
| Tests pass?   | yes
| Fixed tickets | #7832
| License       | MIT
| Doc PR        | no
And if you do that, you can remove the isset check below too