title: AWS S3 change the file extension when using putObject(String,String,String)
body: <p>I'm new to using AWS's S3 and I have to upload a file using the <code>putObject(bucket name, key , string that will become the file)</code> method (makes my life a lot easier).  I was wondering if it's possible to change the extension because when I use this method the file uploaded always has a '.txt' extension, but I need it to be '.csv'. </p>
  
  <p>The code is quite simple:</p>
  
  <pre><code>public void uploadStringFile(String bucket,String username, String fileString) {
      s3Client.putObject(bucket, username, fileString);
  }
  
  awsS3Service.uploadStringFile("ati-teste",fileName, sb.toString());
  </code></pre>