code: public void clear() {
          // Mostly the same as preParse().
          if(isFrozen()) {
              throw new UnsupportedOperationException(
                  "Attempt to clear() a frozen MessagePattern instance.");
          }
          msg=null;
          hasArgNames=hasArgNumbers=false;
          needsAutoQuoting=false;
          parts.clear();
          if(numericValues!=null) {
              numericValues.clear();
          }
      }
docs: Clears this MessagePattern.
  countParts() will return 0.