title: client_secret not required on refresh token azure b2c
body: <p>I have an azure b2c application. When I create a user through the Users application in portal.azure.com (or making a post request with postman) I have to send the client_secret of my b2c app to refresh a token.
  But with users created through Powershell with the azureAD module I have an error saying that I shouldn't send the client_secret.</p>
  
  <pre><code>{
      "error": "invalid_request",
      "error_description": "AADB2C90084: Public clients should not send a client_secret when redeeming a publicly acquired grant.\r\nCorrelation ID: 39abec35-770c-42e6-bd65-438d6501a124\r\nTimestamp: 2018-04-09 14:43:13Z\r\n"
  }
  </code></pre>
  
  <p>Why is that difference? How can I do to create a user that not requires the client_secret using the graph api?</p>
  
  <p>Thanks in advance!
  Germán</p>