Import fails on config files of True/False values pre Umbraco v8.8.0

[KevinJump]

From : https://our.umbraco.com/packages/developer-tools/usync/usync/110465-import-fail-could-not-convert-string-to-boolean-0-path-default-line-2-pos

if you import a true/false value that was generated pre Umbraco 8.8.0 onto a site running Umbraco 8.8+ it fails:

`Import Fail: Could not convert string to boolean: 0 Path 'Default', line 2, pos....`

this is because of breaking change #8477 in Umbraco released in Umbraco 8.4

pre v8.8

{
  "Default": null,
  "Label": null
}

8.8.0+

{
  "Default": false,
  "ShowLabels": false,
  "LabelOn": null,
  "LabelOff": null
}

the key culprit is the change of Default from string to bool, and the Json serializer can't serialize a null into a bool.

[KevinJump]

Fixed in 8.11.3