code: public <T> void beanClass(Class<T> beanClass)
    {
      validateBeanClass(beanClass);
      
      if (Modifier.isAbstract(beanClass.getModifiers())
          && ! abstractMethods(beanClass)) {
        throw error(L.l("abstract bean class '{0}' is invalid because the abstract methods can't be generated.",
                        beanClass.getSimpleName()));
      }
    }
docs: {@code InjectBuilder.bean(Class)} validation