GenerateChangelog in java

I am trying to generate changelog in the Sybase ASE  using java.

This is how i am creating the liquibase object 

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Now i dont get any command to like liquibase.getchangelog or liquibase.generateChangelog.

What do i do?Plz help

In 3.1.0, there is a new generateChangeLog() method on the Liqubase object that you should be able to use.