code: public void doSetDataSource(DataSource dataSource) {
      if (mediaInfo.get(dataSource) == null) {
        throw new IllegalArgumentException(
            "Don't know what to do with dataSource "
                + dataSource
                + " - either add an exception with addException() or media info with addMediaInfo()");
      }
      this.dataSource = dataSource;
    }
docs: Sets the data source without doing any other emulation. Sets the internal data source only.
  Calling directly can be useful for setting up a {@link ShadowMediaPlayer} instance during
  specific testing so that you don't have to clutter your tests catching exceptions you know
  won't be thrown.
  
  @param dataSource the data source that is being set.
  @see #setDataSource(DataSource)