Yet another generics question: Needs unchecked conversion to conform to ...

I spent a lot of time massaging the code below to avoid a warning,
without success.

I pasted a sample class and inner classes that shows what I want to do.
I wrote two versions of a factory method: one that does not generate
any warnings, and the other generates one.
The return type of the second method is defined like this:

 BeanFactory<Bean> createFactory2(String className){
   ...
 }

The returned BeanFactory is also parametized, and this is where my
problem lies. Can anyone suggest how to avoid the warning, besides
adding a @suppresswarning annotation?

public class Generics {

  public BeanFactory createFactory1(String beanClass)
  throws Exception{

    Class<?> bc = Class.forName(beanClass);

    Class<? extends BeanFactory> bfc =
      bc.asSubclass(BeanFactory.class);

    Constructor<? extends BeanFactory> cstr =
      bfc.getConstructor(new Class[]{});

    return cstr.newInstance(new Object[]{});
  }

  public BeanFactory<Bean> createFactory2(String beanClass)
  throws Exception{

    Class<?> bc = Class.forName(beanClass);

    Class<? extends BeanFactory> bfc =
      bc.asSubclass(BeanFactory.class);

    Constructor<? extends BeanFactory> cstr =
      bfc.getConstructor(new Class[]{});

    // The following line causes the warning:
    return cstr.newInstance(new Object[]{});
  }

  public class BeanFactory<T extends Bean>{
  }

  public class Bean{
  }
}