UUID uuid = new UUID(0, 0x0000000000000000L);
assertEquals(0, uuid.variant());
uuid = new UUID(0, 0x7000000000000000L);
assertEquals(0, uuid.variant());
uuid = new UUID(0, 0x3000000000000000L);
assertEquals(0, uuid.variant());
uuid = new UUID(0, 0x1000000000000000L);
assertEquals(0, uuid.variant());
uuid = new UUID(0, 0x8000000000000000L);
assertEquals(2, uuid.variant());