code: public void release() {
          if (lock != null) {
              try {
                  lock.release();
                  lock = null;
              } catch (IOException ex) {
                  LOGGER.debug("Failed to release lock", ex);
              }
          }
          if (file != null) {
              try {
                  file.close();
                  file = null;
              } catch (IOException ex) {
                  LOGGER.debug("Unable to delete lock file", ex);
              }
          }
          if (lockFile != null && lockFile.isFile()) {
              final String msg = readLockFile();
              if (msg != null && msg.equals(magic) && !lockFile.delete()) {
                  LOGGER.error("Lock file '{}' was unable to be deleted. Please manually delete this file.", lockFile.toString());
                  lockFile.deleteOnExit();
              }
          }
          lockFile = null;
          removeShutdownHook();
          final Timestamp timestamp = new Timestamp(System.currentTimeMillis());
          LOGGER.debug("Lock released ({}) {} @ {}", Thread.currentThread().getName(), magic, timestamp.toString());
      }
docs: Releases the lock on the H2 database.