title: Using AWS (S3) via jclouds - how to assume role
body: <p>When using plain auth credentials I can do:</p>
  
  <pre><code>ContextBuilder.newBuilder("aws-s3").credentials(keyId, key).buildView(BlobStoreContext.class);
  </code></pre>
  
  <p>... to access BlobStoreContext for S3.</p>
  
  <p>In native Amazon java api I can use Security Token Service (STS) to assume role and use temporary credentials to access S3 or any other AWS service.</p>
  
  <p>How do I do this in jclouds?</p>