code: public void put(final String aBucket, final String aKey, final AsyncFile aFile,
              final Handler<HttpClientResponse> aHandler) {
          final S3ClientRequest request = createPutRequest(aBucket, aKey, aHandler);
          final Buffer buffer = Buffer.buffer();
  
          aFile.endHandler(event -> {
              request.putHeader(HttpHeaders.CONTENT_LENGTH, String.valueOf(buffer.length()));
              request.end(buffer);
          });
  
          aFile.handler(data -> {
              buffer.appendBuffer(data);
          });
      }
docs: Uploads the file contents to S3.
  
  @param aBucket An S3 bucket
  @param aKey An S3 key
  @param aFile A file to upload
  @param aHandler A response handler for the upload