About key generated by built-in snowflake algorithm(Sharding-JDBC)

[梁维伟]

Hi.
I found that the result of (the key mod 4) always is 0/1, to me, it is wierd. 
What I expected is, the result should be 0/1/2/3, and the key should evenly 
distributed to all the sharded tables. I am new to ShardingSphere and the 
snowflake algorithm. Hope I can get some help from you. 

Thanks.