// https://github.com/basho/riak-java-client/blob/master/src/main/java/com/basho/riak/client/operations/FetchObject.java
public T execute() throws UnresolvedConflictException, RiakRetryFailedException, ConversionException {
  // fetch, resolve
  Callable<RiakResponse> command = new Callable<RiakResponse>() {                // 1
    public RiakResponse call() throws Exception {
      return client.fetch(bucket, key, builder.build());  // setup call via underlying client
    }
  };
  rawResponse = retrier.attempt(command);                                        // 2
  final Collection<T> siblings = new ArrayList<T>(rawResponse.numberOfValues()); // 3

  for (IRiakObject o : rawResponse) {                                            // 4
    siblings.add(converter.toDomain(o));
  }
      
  return resolver.resolve(siblings);                                             // 5
}