undecorated.rb

path = File.join(ManageIQ::UI::Classic.root, 'app', 'assets', 'images', '100', '*.png')
pngs = Dir.glob(path).map { |f| File.basename(f, '.png') }

Rails.application.eager_load!
models = ApplicationRecord.descendants.reject { |m| m.decorate && (m.decorate.fonticon || m.decorate.fileicon) }.reject do |m|
  ret = nil
  # Some records aren't that easy to create
  begin
    record = m.new
    ret = record.decorate && (record.decorate.fonticon || record.decorate.fileicon)
  rescue
    ret = nil
  end
  ret
end

undecorated = models.map { |m| File.basename(m.to_s.underscore) } & pngs