docs: protected static final BeanContextChild getChildBeanContextChild(Object child)
  	{
  		if (child instanceof BeanContextChild)
  		{
  			if (child instanceof BeanContextProxy)
  			{
  				throw new IllegalArgumentException(Messages.getString("beans.6C"));
  			}
  			return (BeanContextChild) child;
  		}
  		if (child instanceof BeanContextProxy)
  		{
  			if (child instanceof BeanContextChild)
  			{
  				throw new IllegalArgumentException(Messages.getString("beans.6C"));
  			}
  			return ((BeanContextProxy) child).getBeanContextProxy();
  		}
  		return null;
  	}