'To apply the validation of JSON on 'addressJson' or 'locationJson' field, then enter the value of location is {CountryName:India} in Location textbox.
{{jsoninfoForm.controls?.location?.errors?.json.message}}
If you want to apply conditional validation on 'Location Json' then you need to add 'Location' input as {CountryName:India}.
Conditional Expression with type 'string'
{{jsoninfoForm.controls?.locationJson?.errors?.json.message}}
Shows custom message
{{jsoninfoForm.controls?.contactJson?.errors?.json.message}}