@Override
  public boolean equals(@Nullable Object other) {
    if (other == this) {
      return true;
    }
    if (!(other instanceof FirstAvailableDataSourceSupplier)) {
      return false;
    }
    FirstAvailableDataSourceSupplier that = (FirstAvailableDataSourceSupplier) other;
    return Objects.equal(this.mDataSourceSuppliers, that.mDataSourceSuppliers);
  }
{@link DataSource} supplier that provides a data source which will forward results of the first
available data source.

<p>Data sources are obtained in order. Only if the current data source fails, or if it finishes
without result, the next one will be tried.
fbcore/src/main/java/com/facebook/datasource/FirstAvailableDataSourceSupplier.java