They're probably using the BDB Java Edition which uses a GPL-compatible license and does require all source code be released with program distribution.  Looks like you're right, HyperGraphDB can't be LGPL.<p>More info: <a href="http://www.oracle.com/technology/software/products/berkeley-db/htdocs/licensing.html" rel="nofollow">http://www.oracle.com/technology/software/products/berkeley-...</a>