This field is required and in this only alphabets are allowed.
{{userFormGroup.controls.firstName.errors.compose.message}}
validation message based on messageKey
{{userFormGroup.controls.lastName.errors.composeMessageKey.message}}
If you want to apply conditional validation on 'City' then you need to add 'First Name' input as 'Bharat'.
Conditional Expression with type 'string'
{{userFormGroup.controls.city.errors.compose.message}}
This allows alphabets in compose validation
{{userFormGroup.controls.countryName.errors.compose.message}}