code: @SuppressWarnings("WeakerAccess")
    public ApiFuture<Void> dropRowRangeAsync(String tableId, String rowKeyPrefix) {
      return dropRowRangeAsync(tableId, ByteString.copyFromUtf8(rowKeyPrefix));
    }
docs: Drops rows by the specified key prefix and tableId asynchronously
  
  <p>Please note that this method is considered part of the admin API and is rate limited.
  
  <p>Sample code:
  
  <pre>{@code
  ApiFuture<Void> dropFuture = client.dropRowRangeAsync("my-table", "prefix");
  
  ApiFutures.addCallback(
  dropFuture,
  new ApiFutureCallback<Void>() {
  public void onSuccess(Void tableNames) {
  System.out.println("Successfully dropped row range.");
  }
  
  public void onFailure(Throwable t) {
  t.printStackTrace();
  }
  },
  MoreExecutors.directExecutor()
  );
  }</pre>