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: params.rb
    path of file: ./repos/gitlabhq/app/finders/issuable_finder
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

class IssuableFinder
  class Params < SimpleDelegator
    include Gitlab::Utils::StrongMemoize

    # This is used as a common filter for
    
    def project
      strong_memoize(:project) do
        next nil unless project?

        project = project_id.is_a?(Project) ? project_id : Project.find(project_id)
        project = nil unless Ability.allowed?(current_user, :"read_#{klass.to_ability_name}", project)

        project
      end
    end