protected void testClose(
        DataSource<Object> dataSource, DataSource<Object>... underlyingDataSources) {
      dataSource.close();
      if (underlyingDataSources != null) {
        for (DataSource<Object> underlyingDataSource : underlyingDataSources) {
          mInOrder.verify(underlyingDataSource, atLeastOnce()).close();
        }
      }
    }
Verifies that the underlying data sources get closed when data source provided by our
mDataSourceSupplier gets closed.
fbcore/src/test/java/com/facebook/datasource/DataSourceTestUtils.java