docs: public boolean load() {
  
          boolean exists;
  
          if (!DatabaseURL.isFileBasedDatabaseType(database.getType())) {
              return true;
          }
  
          try {
              exists = super.load();
          } catch (Exception e) {
              throw Error.error(ErrorCode.FILE_IO_ERROR,
                                ErrorCode.M_LOAD_SAVE_PROPERTIES, new Object[] {
                  fileName, e
              });
          }
  
          if (!exists) {
              return false;
          }
  
          filterLoadedProperties();
  
          String version = getProperty(hsqldb_compatible_version);
  
          // do not open if the database belongs to a later (future) version
          int check = version.substring(0, 5).compareTo(THIS_VERSION);
  
          if (check > 0) {
              throw Error.error(ErrorCode.WRONG_DATABASE_FILE_VERSION);
          }
  
          version = getProperty(db_version);
  
          if (version.charAt(2) == '6') {
              setProperty(hsqldb_cache_version, "1.6.0");
          }
  
          JavaSystem.gcFrequency = getIntegerProperty(runtime_gc_interval, 0);
  
          return true;
      }