I am surprised that there seems to be no mention of LibreOffice on the HSQLDB site. There are some involved with LibreOffice who would like it not to depend at all on Java, and hence not use HSQLDB. If that happens, HSQLDB is going to lose some, if not a lot of its installations.
So I do suggest that HSQLDB treats LibreOffice on a par with OpenOffice.org and assist LibreOffice with ensuring that HSQLDB works well with LibreOffice-base (see http://wiki.documentfoundation.org/Base).
The references to OpenOffice.org are the result of several years close co-operation between the two projects, which continued until April 2011 (when OpenOffice.org was passed to Apache).
LibreOffice are welcome too. In the past we have worked with developers from RedHat who are now among the participants in this project. We hope to continue co-operation.