code: private Object readResolve() {
          KnownLevel o = KnownLevel.matches(this);
          if (o != null) {
              return o.levelObject;
          }
  
          // Woops.  Whoever sent us this object knows
          // about a new log level.  Add it to our list.
          Level level = new Level(this.name, this.value, this.resourceBundleName);
          return level;
      }
docs: This is a performance optimization.