- Improve Javadoc documentation
- Javadoc: removed unpaired <p>
- Javadoc: removed shouting (bold, caps "MUST")
- Javadoc: document parameters
- Javadoc: no need to write Return in a @return tag
- Javadoc: make correct sentences, not sentence fragments ('Default Db Upgrader.' is not a sentence)
- Remove @Override tag because this won't compile with JDK 5
- Methods in public interfaces don't need to be declared public (Checkstyle detects this, please use Checkstyle as documented)