You can now run the generator, and then override and implement the "validate" methods. Note that the "validate" method of the contentValidation is automatically generated, and you should never override it (Your IDE's Quick Fix won't override it neither).
Complete Example
// ... Imports & Part statements @Modddel( validationSteps: [ValidationStep([ contentValidation, ]),ValidationStep([Validation('blackList',FailureType<PersonBlackListFailure>()), ]) ],)classPersonextendsSimpleEntity<InvalidPerson, ValidPerson> with_$Person {Person._();factoryPerson({requiredAge age,requiredFullName name, }) {return_$Person._create(age: age, name: name); }@overrideOption<PersonBlackListFailure> validateBlackList(person) {/// Notice how we can directly access the fields of `age` and `name`, /// because at this point they are ValidModddels.if (person.name.firstName =='Dash'&& person.name.lastName =='Birdy'&& person.age.value ==28) {returnsome(constPersonBlackListFailure.blackListed()); }returnnone(); }}@freezedclassPersonBlackListFailureextendsValueFailurewith_$PersonBlackListFailure {constfactoryPersonBlackListFailure.blackListed() =_BlackListed;}