public static SimpleFunction<Row, String> getRowToJsonStringsFunction(Schema beamSchema) {
    return new RowToJsonFn<String>(beamSchema) {
      @Override
      public String apply(Row input) {
        return RowJsonUtils.rowToJson(objectMapper, input);
      }
    };
  }
@Test
  public void testGetRowToJsonStringsFunction() {
    for (TestCase<? extends RowEncodable> caze : testCases) {
      String expected = caze.jsonString;
      String actual = JsonUtils.getRowToJsonStringsFunction(caze.row.getSchema()).apply(caze.row);
      assertJsonEquals(caze.userT.toString(), expected, actual);
    }
  }