module ActiveAdmin::OptionalDisplay

def normalize_display_options!
  if @options[:only]
    @options[:only] = @options[:only].is_a?(Array) ? @options[:only] : [@options[:only]]
  end
  if @options[:except]
    @options[:except] = @options[:except].is_a?(Array) ? @options[:except] : [@options[:except]]
  end
end