title: get refresh_token form apigee proxy
body: <p>I have a apigee proxy which returns access_token.I use below command to fetch this access_token</p>
  <pre><code>curl -X POST https://api.xxx.xxx.xxx/xx/oauth2/v1/token -H 'APIKey: ssjjjjsjsjs' -H 'Content-Type: application/x-www-form-unlencoded' --data &quot;code=xxxxxx&amp;redirect_uri=xxx&amp;grant_type=authorization_code&quot;
  </code></pre>
  <p>This gives me access_token successfully.</p>
  <p>Now i have added code to fetch refresh token. And using below call</p>
  <pre><code>curl -X POST https://api.xxx.xxx.xxx/xx/oauth2/v1/refresh-token -H 'APIKey: ssjjjjsjsjs' -H 'Content-Type: application/x-www-form-unlencoded' --data &quot;grant_type=refresh_token&amp;refresh_token=access_token_fetch_from_above_call&quot;
  </code></pre>
  <p>This give me error <code>invalid grant_type</code> .what i am missing here,is this correct way to get refresh_token ?</p>