Problem with Rails 3.0.0.beta2 with Rails :: Generators :: GeneratedAttribute

So, I'm trying to use the rails3 Nifty Generators branch from Ryan Bates. Now I used this gem before it worked with beta-1, but after upgrading to beta2 I got a very strange error.

lib/generators/nifty/scaffold/scaffold_generator.rb:35:in `block in initialize': uninitialized constant Rails::Generators::GeneratedAttribute (NameError)

Pixel code where this happens:

args_for_c_m.each do |arg|
  if arg == '!'
    options[:invert] = true
  elsif arg.include?(':')
    @model_attributes << Rails::Generators::GeneratedAttribute.new(*arg.split(':'))
  else
    @controller_actions << arg
    @controller_actions << 'create' if arg == 'new'
    @controller_actions << 'update' if arg == 'edit'
  end
end

Now I have seen the GeneratedAttribute, which has been used in many gems before, so I'm confused about why it is broken. I'm not sure, but I think this is due to beta2.

So my question is is there a Rails issue of something at my end? If this is at my end, can any ideas I have do wrong?

Thank.