@Nullable
    private synchronized DataSource<T> getDataSourceWithResult() {
      return getDataSource(mIndexOfDataSourceWithResult);
    }
Creates a new data source supplier with increasing-quality strategy with optional lazy state
creation.

<p>Note: for performance reasons the list doesn't get cloned, so the caller of this method
should not modify the list once passed in here.

@param dataSourceSuppliers list of underlying suppliers
@param dataSourceLazy if true, the state of data source would be created only if necessary
fbcore/src/main/java/com/facebook/datasource/IncreasingQualityDataSourceSupplier.java