Enum-backed OptionGroup subclass offered

`EnumBackedOptionGroup`

I built a subclass of OptionGroup backed by an Enum, called EnumBackedOptionGroup. My goal was to simply pass your enum, and its collection of instances would be used to populate the radio buttons of an OptionGroup. I wanted an one-liner, and succeeded. Here's an example usage assuming an enum named `DogBreed`.

OptionGroup optionGroup = new EnumBackedOptionGroup<DogBreed>( "Choose Breed:" , DogBreed.class , DogBreed :: getTitle );

Note how we get type-safety by use of Generics.  

The new Lambda syntax in Java 8 and later lets us pass a method reference to be called to determine the text labeling to be used for each option’s presentation. If you have not yet added such a method, omit that argument and the class falls back to calling `toString`. You need not have mastered Lambda yet; just follow the pattern to call this class.

I would appreciate feedback and criticism. Find the source code pasted at the top of my Answer on StackOverflow.com.

Viritin – `EnumSelect`

By the way, the famous Viritin add-on for Vaadin offers a similar class. I was not able to make that work for me, apparently due to my own confusion. I don’t know exactly how Viritin’s class compares to my new class. I suspect my class might be useful when you want only this one simple feature of passing an enum to build a set of radio buttons without all the many other features of Viritin.