[v5] Custom Validators in field attributes

[ale1981]

PHP: 8.0.16
Laravel: 9.3.1
Backpack-Crud: 5.0.9
Backpack-Pro:1.0.10

Is it possible to add a custom validator when specifying the ValidationRules at field level?
Currently when I attempt to add my custom validator 'measurement' as a string I get the following error;

Method Illuminate\Validation\Validator::validateMeasurements does not exist.