public static HazelcastSqlOperatorTable instance() {
        return INSTANCE;
    }
@Test
    public void testNoOverride() {
        Map<BiTuple<String, SqlSyntax>, SqlOperator> map = new HashMap<>();

        for (SqlOperator operator : HazelcastSqlOperatorTable.instance().getOperatorList()) {
            BiTuple<String, SqlSyntax> key = BiTuple.of(operator.getName(), operator.getSyntax());

            SqlOperator oldOperator = map.put(key, operator);

            assertNull("Duplicate operator \"" + operator.getName(), oldOperator);
        }
    }