Updates to Ionic Angular Toolkit - Schema Validation

I did the steps as written on the page: https://ionic.io/blog/updates-to-ionic-angular-toolkit?_gl=1*1isr9dq*_ga*MTc2OTI3OTIzMC4xNjc0Nzc5MzE4*_ga_REH9TJF6KF*MTY3NTE5MDQ3MS43LjEuMTY3NTE5MzAyMC4wLjAuMA..

I installed @ionic/cordova-builders and changing angular.json from "builder": "@ionic/angular-toolkit:cordova-build" to "builder" : "@ionic/cordova-builders:cordova-build", however, I get the following error when executing the command "ng run myapp:ionic-cordova-build --platform=android":

Schema validation failed with the following errors:
Data path ".builders['cordova-build']" should have required property 'class'.