Return row count when `executeUpdate` run insert sql in Java SDK

`executeUpdate` will return row count when execute insert sql, refer [JDBC Doc](https://docs.oracle.com/javase/7/docs/api/java/sql/Statement.html#executeUpdate(java.lang.String))
Current behavior is return 0

Find the Java SDK's executeUpdate method implementation, likely in a JNI layer or a Java class that calls native C++ code. Check how the row count from the database insert operation is returned. Compare with the JDBC specification linked. Ensure the fix returns the correct inserted row count and update any related tests.

索引モデルが issue の本文から書いたものです。