code: public synchronized void clear(Identifier rootId, boolean enableCache)
    {
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        tc.entry(this,cclass, "clear");
      matchTree = null;
      matchTreeGeneration = 0;
      subExpr.clear();
      
      // Now reinitialise the matchspace
      initialise(rootId, enableCache);
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        tc.exit(this,cclass, "clear");
    }
docs: Removes all objects from the MatchSpace, resetting it to the 'as new'
  condition.