  @Test
  public void testApi() {

    DataTable table1 = tableEnv.sqlQuery("select * from test.t1");
    Assert.assertNotNull(table1);
    DataTable table2 = tableEnv.sqlQuery("select * from t2");
    Assert.assertNotNull(table2);
    Assert.assertEquals("hello,marble",
        tableEnv.sqlQuery("select hello('marble') as c1")
            .toMapList()
            .get(0)
            .get("c1"));
  }