Adds the config option as a value of a property in order to make a property a constant. And example would be:
.public({
    myProperty: {
        constant: true,
        value: 5;
    }
});
The option called "value" of the object will be the value in this example, but the whole config object can be used instead of just the value property. In the future, this config object may will have more options.