docs: private void primDeleteExpired(
              Date expiration, Class entityType, String entityKey, Connection conn)
              throws LockingException, SQLException {
          Statement stmnt = null;
          Timestamp ts = new Timestamp(expiration.getTime());
  
          StringBuffer buff = new StringBuffer(100);
          buff.append("DELETE FROM " + LOCK_TABLE + " WHERE " + EXPIRATION_TIME_COLUMN + LT);
          buff.append(printTimestamp(ts));
          if (entityType != null) {
              Integer typeID = EntityTypesLocator.getEntityTypes().getEntityIDFromType(entityType);
              buff.append(" AND " + ENTITY_TYPE_COLUMN + EQ + typeID);
          }
          if (entityKey != null) {
              buff.append(" AND " + ENTITY_KEY_COLUMN + EQ + sqlQuote(entityKey));
          }
  
          String sql = buff.toString();
  
          if (log.isDebugEnabled()) log.debug("RDBMEntityLockStore.deleteExpired(): " + sql);
  
          try {
              stmnt = conn.createStatement();
              int rc = stmnt.executeUpdate(sql);
              if (log.isDebugEnabled()) {
                  String msg = "Deleted " + rc + " expired locks.";
                  log.debug("RDBMEntityLockStore.deleteExpired(): " + msg);
              }
  
          } catch (SQLException sqle) {
              throw new LockingException("Problem deleting expired locks", sqle);
          } finally {
              if (stmnt != null) stmnt.close();
          }
      }