How do I modify the Javadoc when I modify someone else's code?

I am working on someone else's code and making significant modifications. (I am converting it to use a different database than the one he originally used.) How do I indicate in the Javadoc comments that I am not the original author of the code, but that I did make contributions to it. Is there a clean or standard way of doing this already? My Googling is not helping me figure this out.

Example:

/**
* This class does some really awesome stuff.
* 
* @author Steph the Great - Modified to use PostgreSQL instead of Derby;
*         added comments to the code
*/

I also don't know the original author's name, so all I can put down is myself . . .