title: Generating access token from refresh token using oauth2 in django
body: <p>I am trying to generate acces token from refresh token in django.
  I am using Oauth2.
  I am using oauth2 internal url for generating access token
  i.e, 127.0.0.1:8000/o/token/
  I am testing this in Rest Console.</p>
  
  <p>My request is:</p>
  
  <pre><code>{ "client_id": "m5JjAzkqOCdH9MC4KV9EAjKuNhdMv2TyNDXgD6T7", "client_secret": "6C495R1BiA0lfXgm7lh0Zvqc6ugB7H6srlwSCLwyVNgoKqK7xGVQbB63Hj97E7fw3tWIgG7tnv9K5nwInaKPaaqSy4FLm8jaBdTPZ8YzlCJMkuiWNbIwc0ltFB7H9cgq",
   "username": "lalit198910",
   "grant_type": "refresh_token",
  "token type" : "Bearer",
  "refresh_token": "1svsHogo5tq6UxkiY55iMvMpWnGRsn" }
  </code></pre>
  
  <p>the error i am getting is:</p>
  
  <pre><code>"error": "unsupported_grant_type"
  </code></pre>
  
  <p>my content type is :</p>
  
  <pre><code>application/x-www-form-urlencoded
  </code></pre>
  
  <p>In Custom headers i have :</p>
  
  <pre><code>authorization type:  bearer
  
  
  value :3nKkSW9TEPjusuy2PzKhFxoTkFlqQC(Access token)
  </code></pre>