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: policy.rb
    path of file: ./repos/powerstation/powerstation/lib/compiled-jruby/lib/ruby/stdlib/rubygems/security
    
    the code of the file until where you have to start completion: require 'rubygems/user_interaction'

##
# A Gem::Security::Policy object encapsulat
    
  def subject certificate # :nodoc:
    certificate.extensions.each do |extension|
      next unless extension.oid == 'subjectAltName'

      return extension.value
    end

    certificate.subject.to_s
  end