Sample request with `curl`:

```sh
curl -XPOST 'http://localhost:9001/?Action=AssumeRoleWithCustomToken&Version=2011-06-15&Token=aaa&RoleArn=arn:minio:iam:::role/idmp-vGxBdLkOc8mQPU1-UQbBh-yWWVQ'
```

Prettified Response:

```xml
<?xml version="1.0" encoding="UTF-8"?>
<AssumeRoleWithCustomTokenResponse xmlns="https://sts.amazonaws.com/doc/2011-06-15/">
  <AssumeRoleWithCustomTokenResult>
    <Credentials>