title: Using file as payload in Advanced REST Client
body: <p>I'm trying to work with the Advanced REST Client of Google.
  I installed the extension, and I can work with it.
  Now I wanted to use a JSON-file as input for my payload.</p>
  
  <p>The JSON-file looks as follows :</p>
  
  <pre><code>{"UserName":"", "UserPassword":"","SetDebug":true}
  </code></pre>
  
  <p>The Content-Type is set to application/json.</p>
  
  <p>But when I try to send the request I get the following error:</p>
  
  <blockquote>
    <p>{
    "Message": "The request entity's media type 'multipart/form-data' is not supported for this resource."
    }</p>
  </blockquote>
  
  <p>What am I doing wrong? Can anyone help me?</p>