public static boolean remove(final String urlHash) {
   if (urlHash == null) return false;
   Map<String, InitExecEntry> resultStack;
   for (final EventOrigin origin : EventOrigin.values()) {
     resultStack = getStack(origin);
     if (resultStack != null) resultStack.remove(urlHash);
   }
   return true;
 }
 static {
   for (final EventOrigin origin : EventOrigin.values()) {
     resultStacks.put(origin, new LinkedHashMap<String, InitExecEntry>());
     resultDomains.put(origin, new ClusteredScoreMap<String>(true));
   }
 }
 public static void clearStacks() {
   for (final EventOrigin origin : EventOrigin.values()) clearStack(origin);
 }