You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: add_activity_icon.rb
    path of file: ./repos/redmine_jenkins/lib/redmine_jenkins/hooks
    
    the code of the file until where you have to start completion: module RedmineJenkins
  module Hooks
    class AddActivityIcon < Redmine::Hook::ViewListener

      def view_layouts_ba
    
      def view_layouts_base_html_head(context={})
        project = context[:project]
        return '' unless project
        controller = context[:controller]
        return '' unless controller
        action_name = controller.action_name
        return '' unless action_name

        if (controller.class.name == 'ActivitiesController' and action_name == 'index')
          return stylesheet_link_tag(:application, plugin: 'redmine_jenkins')
        end