code: @Override
      public Promise<Void> copy(String from, String to) {
          return adapter.toPromise(handler -> vertx.fileSystem().copy(from, to, handler));
      }
docs: Copy a file from the path {@code from} to path {@code to}, asynchronously.
  <p>
  The copy will fail if the destination already exists.
  
  @param from the path to copy from
  @param to   the path to copy to
  @return a promise for completion