title: Rest-Assured Audio File Upload with multipart/mixed
body: <p>I'm trying to test the following upload content in rest-azure. It's a multipart/mixed and the first part is the body and the second part is the actual audio file:</p>
  
  <pre><code>PUT /baseUri/service/v1/audio/14255894558 HTTP/1.1
  Host: p18web.stg.example.com
  Authorization: Basic XXXXXXXXXXXXXXXX
  Content-Type: multipart/mixed; boundary="====outer123=="
  Cache-Control: no-cache
  
  
  --====outer123==
  Content-Disposition: form-data; name="request";
  Content-Type: application/json; charset=UTF-8
  
  {
    "object": {
    "parentFolderPath": "Media/VR",
     "attributes": {
       "attribute": [
        {
        "name": "Date",
        "value": "2014-03-17T12:37:59Z"
      },
      {
        "name": "Message-Id",
        "value": "950124.162336@example.com"
          }
        ]
      }
    }
  }
   --====outer123==
   Content-Disposition: form-data; name="attachment"; filename="";Content-ID: 
   duicw78fhage7f
   Content-Type: audio/wav
  
   UklGRjItFABXQVZFZm10IBAAAAABAAIARKwAABCxAgAEABAAZGF0YZgsFACn/5X/ff+D/xb/Hf8q/wP/fwAQANACQwJHBdMEGwfZBlEIOghmCVMJoAqdCt0L5QvkDP4MLw4yDjoQGBB/EygTZRjEF08fWh40KAUnvjHWMDI5IjljPIo9tDuXPZw5mTv1OH06hzqoO7088z3aPWY/Nz0ZP8A7oD3hOnk83DvuPOQ+iz81Q7tDHEfjRwhJWEr7SKhKcEgSSgxJSUowSzNMdE2RTvZNnU+ITHlOt0p3TJxK0ksETbxNxFBkUYlTiFRsVMdV/FQzVtNXWlh2/nfUduZ3u3bQd6t2tXefdq93gHaJd292d3djdmZ3QHZOdyx2L3cadiF3AXYGd+t17nbrdeJ2w3XOdrB1o3aqdaB2kXWWdnh1dnZvdWZ2YHVUdjp1OHYvdSt2IXUadgh1/XX1dOt15nTfddV0xnW5dKh
  
  --====outer123==--
  </code></pre>
  
  <p>I created the below test but unfortunately, it's not working:</p>
  
  <pre><code>  @Test
    public void uploadAudio(){
  
      Map&lt;String, String&gt; jsonRequest = new HashMap&lt;&gt;();
      jsonRequest.put("Content-Disposition", "form-data");
  
      Map&lt;String, String&gt; jsonAttachment = new HashMap&lt;&gt;();
      jsonAttachment.put("Content-Disposition", "form-data");
      jsonAttachment.put("Content-ID", "duicw78fhage7f");
  
      given()
         .contentType("multipart/mixed; boundary=====outer123==")
         .multiPart("text", dataProvider.getAudioAttachment())
         .multiPart(new MultiPartSpecBuilder(jsonRequest).with().controlName("request")
                 .and().mimeType(ContentType.JSON.withCharset("UTF_8")).build())
         .multiPart(new MultiPartSpecBuilder(jsonAttachment).with().controlName("attachment")
                 .and().emptyFileName().and().mimeType("audio/wav").build())
         .queryParam("msisdn", "14565894558")
         .header("Authorization", "Basic xxxxxxxx")
         .header("Cache-Control", "no-cache")
         .body(dataProvider.getWSGUploadAudioRequest()).
      expect()
         .statusCode(200).
      when()
         .put("https://&lt;host&gt;/&lt;service&gt;/v1/audio/{msisdn}");
  
  
  }
  </code></pre>
  
  <p>I've tested this case many times and it seems like the issue is with the multipart body combination although I don't know exactly which causes this issue. Can I please assist? I'm using the latest version of rest-assured</p>