code: public static Class<? extends Iced> getImplClass(Class<? extends Schema> clz) {
      Class<? extends Iced> impl_class = ReflectionUtils.findActualClassParameter(clz, 0);
      if (null == impl_class)
        Log.warn("Failed to find an impl class for Schema: " + clz);
      return impl_class;
    }
docs: Return the class of the implementation type parameter I for the
  given Schema class. Used by the metadata facilities and the
  reflection-base field-copying magic in PojoUtils.