(Quick Reference)
                min
Purpose
Ensures a value does not fall below a minimum value.
Examples
age min: new Date()
price min: 0F
Description
Sets the minimum value of a class that implements 
java.lang.Comparable. The type of the value must be the same as the property.
Note that constraints are only evaluated once which may be relevant for a constraint that relies on a value like an instance of 
java.util.Date.
class User {
    ...    static constraints = {
        // this Date object is created when the constraints are evaluated, not
        // each time an instance of the User class is validated.
        age min: new Date()
    }
}This constraint influences 
schema generation.
Error Code: 
className.propertyName.min.notmet