Support of Adding Custom Methods to the Dynamic Beans.

When the document beans are generated on the fly, there is no option to add some custom methods to the generated bean.
If the developer wants to add custom methods and shows them in the freemarker template, it could be a nice feature to be able to support enhancing the existing bean.
The developer creates a document bean class, adds his custom methods and sets the class as enhanceable. Then dynamic bean service creates a new class extending
from that bean class and returns the generated bean class.