@Override
    public String getDisplayName()
    {
        return "map(" + keyType.getDisplayName() + ", " + valueType.getDisplayName() + ")";
    }
@Test
    public void testMapDisplayName()
    {
        MapType mapType = new MapType(
                BIGINT,
                createVarcharType(42),
                MethodHandleUtil.methodHandle(TestMapType.class, "throwUnsupportedOperation"),
                MethodHandleUtil.methodHandle(TestMapType.class, "throwUnsupportedOperation"));
        assertEquals(mapType.getDisplayName(), "map(bigint, varchar(42))");

        mapType = new MapType(
                BIGINT,
                VARCHAR,
                MethodHandleUtil.methodHandle(TestMapType.class, "throwUnsupportedOperation"),
                MethodHandleUtil.methodHandle(TestMapType.class, "throwUnsupportedOperation"));
        assertEquals(mapType.getDisplayName(), "map(bigint, varchar)");
    }