You can try to use the Firebird Database within LibreOffice which doesn’t need Java. This feature is still marked as experimental. Firebird Databases are available since LibreOffice 4.2. (see the release notes for further information

To turn the experimental features on, you have to go to the Settings –> LibreOffice –> Advanced –> “Enable experimental features” (see screenshot bellow)

Then you can uncheck the Java from the same Dialog.

There are few components written in Java if you use them :The Wizards, Report Builder, and Report Designer sub-components are written in Java. Full list of Java dependencies here.

Original question and source is on ask.libreoffice.org

To make Firebird Embedded default database in the new database dialog open Expert Configuration and change this key

org.openoffice.Office.DataAccess/EmbeddedDatabases/DefaultEmbeddedDatabase/Value to sdbc:embedded:firebird