}
    // At this point, it's either a raw class or parameterized type.
    checkArgument(
        getRawType().isAssignableFrom(subclass), "%s isn't a subclass of %s", subclass, this);
    Type resolvedTypeArgs = resolveTypeArgsForSubclass(subclass);
    @SuppressWarnings("unchecked") // guarded by the isAssignableFrom() statement above
    TypeToken<? extends T> subtype = (TypeToken<? extends T>) of(resolvedTypeArgs);
    checkArgument(