title: Intent with required parameter showing the count of items
body: <p>trying to make an Intent for my first Conversational Assistant with a couple of parameters. Everything is build in Dialogflow and for some of my functionality I use fulfillment.</p>
  
  <p>The easiest way to describe my assistant is as a cinema tickets booking.</p>
  
  <p>I need to store @number_of_tickets, @cinema, @movie. The last two (@cinema and @movie) are very easy to solve with entities, however struggle a lot with @number_of_tickets. All of this parameters should be mandatory.</p>
  
  <p>My goal is to allow such kind of functionality:</p>
  
  <ol>
  <li>Book me a ticket for Star Wars in IMax (ticket = 1 = @number_of_tickets, Star Wars = @movie, IMax = @cinema)</li>
  <li>Book me 2 tickets for Star Wars in IMax(2 tickets = 2 = @number_of_tickets, Star Wars = @movie, IMax = @cinema)</li>
  <li>Book me tickets for Star Wars in IMax -> How many tickets you want to book?</li>
  </ol>
  
  <p>I tried with composite Entities but it doesn't work as I'm expecting.</p>
  
  <p>How I can enable such kind of functionality in Dialogflow?</p>
  
  <p>Is there a way to require @number_of_tickets to be between 1 and 5?</p>