function generateSampleDummyData() {
  var tableSchema = db.getSchema().getDummyTable();

  var row1 = tableSchema.createRow({
    string: 'string1',
    number: 100,
    integer: 100,
    string2: 'string21',
    boolean: false,
    datetime: new Date()
  });

  var row2 = tableSchema.createRow({
    string: 'string2',
    number: 200,
    integer: 200,
    string2: 'string22',
    boolean: false,
    datetime: null
  });

  return [row1, row2];
}
Creates two sample rows. One with a specified 'datetime' and one
with a null 'datetime'.
@return {!Array<!hr.db.row.DummyTable>}