public Set<String> getColumnNames() {
    if (_columnNames == null) {
      throw new IllegalStateException("CSV column names must be set in " + this.getClass().getSimpleName()
          + " if the fields to extract are not explicitly provided.");
    }
    return _columnNames;
  }
@Test
  public void testSetColumnNamesEnforced() {
    CSVRecordExtractorConfig recordExtractorConfig = new CSVRecordExtractorConfig();
    try {
      recordExtractorConfig.getColumnNames();
    } catch (IllegalStateException e) {
      // Expected exception thrown
      return;
    }
  }