Raise a predefined or custom message (Multipart Validation Message) via Groovy in CX Sales

In the CX Sales application we can create new messages, or see predefined messages via Setup and Maintenance → Manage Messages task. Their Translations can be managed via the User Interface Text, where they are called Multipart Validation Messages.

See for creation these messages.

How can we raise or get the text of these defined messages via Groovy triggers?