Are you planning to use AmendmentEntity for persistence? (i.e. is it going to be mapped onto a table/view) ? If not, you could just create a class and not implement IEntity2: it's a bit unclear why you did implement that interface on this class.
To use the DI functionality, from the constructor, call:
DependencyInjectionInfoProviderSingleton.PerformDependencyInjection(this);
so you pass the instance to inject stuff into to the method.