code: @Override
  	public boolean hasMoreData(final String dataSetKey) {
  		List<? extends DataSource> dataSources = dataSourcesProvider.get();
  		for (DataSource ds : dataSources) {
  			if (ds.hasMoreData(dataSetKey)) {
  				return true;
  			}
  		}
  		return false;
  	}
docs: {@inheritDoc}
  
  @return {@code true}, as long as any of the contained data sources has more data available
  for the specified key