插入时没有平分到其他数据库

参考Quick-Start，使用jdbc插入几百条数据只会插入到dbtest2数据库，没有平分到其他数据库。
查询、修改正常。

rule.xml用的默认配置。

Start with the Quick-Start instructions and the default rule.xml configuration, then reproduce the issue using JDBC to insert several hundred rows. Compare the insert routing with the query and update behavior; the work is done when inserts are distributed across the configured databases rather than only dbtest2.

Written by the indexing model from the issue text.